Question

there are 12 boys and 10 girls in the gym class. If 6 more boys joined , how many more girls are needed to stay at the same ratio.

Answer 1

$\frac{12}{10}= \frac{18}{x}$
cross multiply
12x=180
divide both sides by 12
x=15
if their is 10 girls, then you need 5 more to keep the ratio.