There were 198 children enrolled in the Gillian Dancing School in 2022. ⁵₁₁ of the children were boys. Additional children joined the dancing school in 2023. For every 5 boys who joined the dancing school, 4 girls joined the dancing school. If there was an equal number of girls and boys in 2023, how many girls joined the school in that year?

	Boys	Girls
Before	90	108
Change	+ 5 u	+ 4 u
After	90 + 5 u	108 + 4 u

Fraction of children who are girls
= 1 - ⁵₁₁
= ⁶₁₁

Number of boys at first
= ⁵₁₁ x 198
= 90

Number of girls at first
= ⁶₁₁ x 198
= 108

Boys who joined : Girls who joined
5 : 4

The number of girls and boys in the end is the same.

90 + 5 u = 108 + 4 u
5 u - 4 u = 108 - 90

1 u = 18

Number of girls who joined the school in that year
= 4 u
= 4 x 18
= 72

Answer(s): 72