Tutor MathsGuru: Ask me for your burning Maths questions!

[Dharma]

little_twin_stars:

Dear all, pls help me to understand this qn....


TIA.


20% of John's savings was $120 more than 30% of Brian's savings. After John spent 5/6 of his savings and Brian spent 1/6 of his savings, John had $20 more than Brian. Find the savings of John at first.


Although I have the answer key... I cannot understand how it worked out.

Pls help... Thank you very veyr much

John’s savings = 30u
Brian’s savings = 30p

20% of 30u = 30% of 30p + $120
6u = 9p + $120 ------------- ( 1 )

(5/6 x 30u) – (1/6 x 30p) = $20
25u – 5p = $20 -------------- (2)

You have 2 equations and 2 unknowns; you can solve the qn

John’s savings ate first = 30u = 30 x ?

[little_twin_stars]

Thanks…


but call me dumb, ignorant… but why 30u and 30p?

The simultaneously equation part I understand liao… but

haiz…

help …

[Dharma]

little_twin_stars:

Thanks...


but call me dumb, ignorant... but why 30u and 30p?

The simultaneously equation part I understand liao... but

haiz...

help ...

Wanted to avoid decimals when it comes to multiply by 20%, 30% or even the fractions. So, I try to make life easy.

You can use 6u & 6p or any of its multiples…. No problem.

[little_twin_stars]

okay, i understood already...


thanks a lot

[Carrot]

Hi thank you in advance please help me stuck on this question:


Mr Ho used to travel at a speed of 80km/h from town A to town B. He slowed down his speed to 60km/h and reached town B 1 1/2 hours later than usual. Find the distance between town A and Town B.

:?: :?: :?:
Thanks !

[Yu Xuan]

Carrot:

Hi thank you in advance please help me stuck on this question:


Mr Ho used to travel at a speed of 80km/h from town A to town B. He slowed down his speed to 60km/h and reached town B 1 1/2 hours later than usual. Find the distance between town A and Town B.

:?: :?: :?:
Thanks !

Speed Ratio:
Usual : Slower
80 : 60
4 : 3

Time Ratio
Usual : Slower
3 : 4

4u - 3u = 1 1/2h
1 u = 1 1/2h

1 1/2h * 3 = 4 1/2h
4 1 /2h * 80 = 360km

Is 360km that the answer?

[Vanilla Cake]

Carrot:

Mr Ho used to travel at a speed of 80km/h from town A to town B. He slowed down his speed to 60km/h and reached town B 1 1/2 hours later than usual. Find the distance between town A and Town B

Constant distance
Ratio of speed
80 : 60
4 : 3

Ratio of time
3 : 4

Difference in time = 1u = 1½ h = 1.5 h

Distance travelled @ 80 km/h -> 3ux80 = 3x1.5x80 = 360 km
or
Distance travelled @ 60 km/h -> 4ux60 = 4x1.5x60 = 360 km

Distance between town A and Town B was 360 km.

OR

Using algebra and let the distance between town A and Town B be D.
Form an equation to solve:

D/80+3/2=D/60
(D+120)/80=D/60
80D = 60D+7200
20D = 7200
D = 360

Distance between town A and Town B was 360 km.

[starlight1968sg]

Hi,

A pet shop owner bought some cans of dog food. He divided the dog food equally among his dogs.
If he bought 7 cans for each dog, he would have bought 4 extra cans.
If he bought 11 cans for each dog, he would need 28 more cans.
(a) How many dogs were there in the pet shop?
(b) How many cans did the owner buy?

I am confused!

Many thanks.

[Brenda10]

starlight1968sg:

Hi,

A pet shop owner bought some cans of dog food. He divided the dog food equally among his dogs.
If he bought 7 cans for each dog, he would have bought 4 extra cans.
If he bought 11 cans for each dog, he would need 28 more cans.
(a) How many dogs were there in the pet shop?
(b) How many cans did the owner buy?

I am confused!

Many thanks.

Hi, the question is familar but can't recall from which paper.

11 - 7 = 4
4 + 28 = 32
32 /4 = 8 (dogs)

8 x 7 + 4 = 60 (cans the owner buy)

Hope the abvoe useful. :lol:

[Yu Xuan]

starlight1968sg:

Hi,

A pet shop owner bought some cans of dog food. He divided the dog food equally among his dogs.
If he bought 7 cans for each dog, he would have bought 4 extra cans.
If he bought 11 cans for each dog, he would need 28 more cans.
(a) How many dogs were there in the pet shop?
(b) How many cans did the owner buy?

I am confused!

Many thanks.

By giving each dog 4 more cans, he use up the extra 4 cans and needed another 28 more.

Hence
28 + 4 = 32
32 / 4 = 8

a) 8 dogs

b) (7 * 8 ) + 4 = 60