Answer:

Step-by-step explanation:
=> 
Dividing both sides by -4
=> 
=> 
So this sheet is about area and perimeter, focus hard on it and it would be a good idea if you had a spare piece of paper next to you for figuring it out

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.