librastar666:

Hi, can someone help on these question?


1) There were a total of 930 boys and girls at a carnival.
After 4/5 of the boys and 3/4 of the left, there were 120 more girls than boys that remained. How many boys were at the carnival at first?

Many thanks in advance. :thankyou:

The strategy is important. Most students will start to find common denominator, which further complicates the problem.

Assume there are 5u number of boys, and 4v number of girls.

After 4/5 of boys and 3/4 of girls left, there are 1/5 of boys and 1/4 of girls left.

So 1v = 1u + 120.
Therefore 4v = 4u + 480.

Draw a model, you will see that 5u + 4u + 480 = 930. u = 50.



Cheers,