Given:
number of girls: 96
ratio girls to boys : 4:5
find the number of boys:
96 / 4 = 24 * 5 = 120 number of boys
4:5 ⇒ 96 :120
Additional boys arrived making the ration 2:3
96/2 = 48 * 3 = 144 number of boys
144 - 120 = 24 additional boys arrived.
2:3 ⇒ 96:144