Homework Help: math

Posted by sylvie on Friday, February 12, 2010 at 4:22pm.

The number of boys in a certain class exceed the number of girls by 7. If the number of boys is 5/4 of the number of girls, how many boys are there in the class?

The choices of answers are:

a) 21
b) 28
c) 35
d) 42
e) 63

I figured out that the answer is 35, but I did it by subtracting each of the possible answers by 7 and then multiplying that answer by 5/4.

This is what I did to get my final answer using 35: 35 - 7 = 28; 5/4 X 28/1 = 140/4 which equals 35.

Now, I know there must be a simplier way to get that answer.

Can you show me step by step? Thanks.

math - bobpursley, Friday, February 12, 2010 at 4:41pm
B-7=G
B= 5/4 * G = 5G/4
5G/4-7=G
5G-28=4G
G=28
B=28+7=35
G=28
math - Sylvie, Friday, February 12, 2010 at 6:24pm
Thanks very much.

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