Q&A - P5 Math

[the shadowed snake]

Hi how to do this


In a bus, there were 40% as many children as adults. After 22 adults alighted from the bus the percentage of the children increased to 60%. How many children were there in the bus?

[php]

the shadowed snake:

Hi how to do this


In a bus, there were 40% as many children as adults. After 22 adults alighted from the bus the percentage of the children increased to 60%. How many children were there in the bus?

Before : C --> 7u x 3 = 21u A --> 5u x 3 = 15u
After : C --> 3p x 7 = 21u A --> 2p x 7 = 14u

1u = 22
21u = 22x21 = 462

[happyheart]

cimman:

happyheart:

Hi, I need help on this...please help with illustration. I am confused with multiple variables and the 3 equations. Thank you!


The cost of 6 identical chairs , 5 identical lamps and 1 table is $380.
The cost of 2 such chairs and 1 table is $188, while 1 chair and 1 lamp cost $44.
a) What is the cost of 1 chair and 1 table?
b) What is the total cost of 1 table, 1 lamp and 1 chair?

if you use a table, it will be easier to see the relationships:
first put all the equations into a table (I should put l for lamps, but l looks like a 1 or I, so I use p to represent unit cost for lamps) :
http://i47.tinypic.com/35ba3ys.png\">

next fill up the blank boxes with zeros and determine which variable you want or don't want by putting a tick and cross in the right places:
http://i50.tinypic.com/2vm94iv.png\">

substitute p and solve for c + t
http://i48.tinypic.com/24o8xg5.png\">

put in the new equation (c + t) into the table:
http://i50.tinypic.com/289lrgw.png\">

this is a possible way:
http://i47.tinypic.com/14p9o9.png\">

there are other ways, you can use equation 2 - equation 3, here I'm using equation 2 - equation 4, which I think is easier to \"see\":
http://i46.tinypic.com/2q15hlh.png\">

c = 28. Once you have the value of c, you can find t and p.

Thank you Cimman, that is one way to look at it. Much appreciated!

[happyheart]

chloecube:

i hope its not to confusing for u,


6C + 5L + 1T = 380 ---Equation 1
2C + 1T = 188 ---Equation 2
1C + 1L = 44 ---Equation 3

Equation 1 - Equation 3
5C + 4L + 1T = 336---Equation 4

Equation 2 + Equation 3
3C + 1L + 1T = 232---Equation 5

Equation 4 - Equation 5
2C + 3L = 104

Equation 3 (x2)
2C + 2L = 88

from above, u can find out that 1L = 16
1C = 44-16=28
6C + 5L + 1T = 380
168 + 80 + 1T = 380
1T = 132

Yes, I can understand this one. The challenge I faced earlier was to first break down the various equations. Thank you.

[Udon]

Good Morning,

Appreciate your help on the following questions.
Thanks for your time.


Q1. Ali and Tom had the same amount of money. After Ali spent $280 and Tom spent 1/5 of his money, the ratio of money they had left was 3:8 respectively.

(a) How much money did Ali have at first?
(b） Find the amount of money Tom had left.


Q2. At a bakery, there was an equal number of doughnuts and cup cakes. After 24 more doughnuts were baked and 8 cup cakes were sold, there were thrice as many doughnuts as cup cakes.

(a) What was the total number of doughnuts and cup cakes at the bakery at first?
(b) What was the total number of doughnuts and cup cakes at the bakery in the end?

[chloecube]

happyheart:

chloecube:

i hope its not to confusing for u,


6C + 5L + 1T = 380 ---Equation 1
2C + 1T = 188 ---Equation 2
1C + 1L = 44 ---Equation 3

Equation 1 - Equation 3
5C + 4L + 1T = 336---Equation 4

Equation 2 + Equation 3
3C + 1L + 1T = 232---Equation 5

Equation 4 - Equation 5
2C + 3L = 104

Equation 3 (x2)
2C + 2L = 88

from above, u can find out that 1L = 16
1C = 44-16=28
6C + 5L + 1T = 380
168 + 80 + 1T = 380
1T = 132

Yes, I can understand this one. The challenge I faced earlier was to first break down the various equations. Thank you.

ya, me too
but i've learnt alot from this forum, esp from Tianzhu and Mathizzfun

[tianzhu]

Udon:

Q2. At a bakery, there was an equal number of doughnuts and cup cakes. After 24 more doughnuts were baked and 8 cup cakes were sold, there were thrice as many doughnuts as cup cakes.

(a) What was the total number of doughnuts and cup cakes at the bakery at first?
(b) What was the total number of doughnuts and cup cakes at the bakery in the end?

Hi

Hope this helps.

Best wishes

http://farm8.staticflickr.com/7071/7367596916_321446c807_z.jpg\">

[the shadowed snake]

php:

the shadowed snake:

Hi how to do this


In a bus, there were 40% as many children as adults. After 22 adults alighted from the bus the percentage of the children increased to 60%. How many children were there in the bus?

Before : C --> 7u x 3 = 21u A --> 5u x 3 = 15u
After : C --> 3p x 7 = 21u A --> 2p x 7 = 14u

1u = 22
21u = 22x21 = 462

Hi php
The ans in the book is 12

Someone help me :?: :?: :?: :?: :?: :?: :?: :?: :?: :?: :?: :?: :?: :?: :?: :?: :?: :?:

[MathIzzzFun]

the shadowed snake:

php:

[quote=\"the shadowed snake\"]Hi how to do this


In a bus, there were 40% as many children as adults. After 22 adults alighted from the bus the percentage of the children increased to 60%. How many children were there in the bus?

Before : C --> 7u x 3 = 21u A --> 5u x 3 = 15u
After : C --> 3p x 7 = 21u A --> 2p x 7 = 14u

1u = 22
21u = 22x21 = 462

Hi php
The ans in the book is 12

Someone help me :?: :?: :?: :?: :?: :?: :?: :?: :?: :?: :?: :?: :?: :?: :?: :?: :?: :?:[/quote]Hi

the number of children remained the same before and after 22 adults alighted.

At first, children : adult --> 2 : 5
In the end, children : adult --> 3 : 2

number of children remained the same, so we have:
at first, children : adult --> 6u : 15u }
in the end, children : adult --> 6u : 4u } 11u adults alighted

11u --> 22, 1u --> 2
children --> 6 x 2 = 12

cheers.

[tianzhu]

Udon:

Q1. Ali and Tom had the same amount of money. After Ali spent $280 and Tom spent 1/5 of his money, the ratio of money they had left was 3:8 respectively.

(a) How much money did Ali have at first?
(b） Find the amount of money Tom had left.

Hi

Hope this helps.

Best wishes

http://farm9.staticflickr.com/8147/7182529523_ab2d13d36f_z.jpg\">