I would answer but i can not see what it says.... Sorry
You could understand the ration as parts: the total number of parts was 3+7=10.
So girls were 3/10 parts and boys 7/10 parts. The difference was 7-3=4 parts. this difference is equal to 360, so each part is 90 (4*90 =360).
so girls are "3 parts" and each part is 90, then the number of girls is 3*90=270.
The number solution set 2 . 30 36
