Question

There are 12 boys and 10 girls in your gym class. If 6 boys joined the class, how many girls would need to join for the ratio of boys to girls to remain the same?

Answer 1

What do you think?

I'll give you a hint: whenever you add something to one side, in order to keep the difference equal youuuuuu-?

Answer 2

find the common ratio e.g if they gave 20:10 the ration would be 10:5

Answer 3

turn the ratios into fractions
12 over 10 & 18 over x
cross multiply
10 x 18 = 180
divide 180 by 12.
180 / 12 = 15
check to make sure they are equivalent
15 - 10 = 5
answer: 5 girls would need to join the class.