There were 297 children enrolled in the Yen Dancing School in 2016. ⁴₁₁ of the children were boys. Additional children joined the dancing school in 2017. For every 4 boys who joined the dancing school, 3 girls joined the dancing school. If there was an equal number of girls and boys in 2017, how many girls joined the school in that year?

	Boys	Girls
Before	108	189
Change	+ 4 u	+ 3 u
After	108 + 4 u	189 + 3 u

Fraction of children who are girls
= 1 - ⁴₁₁
= ⁷₁₁

Number of boys at first
= ⁴₁₁ x 297
= 108

Number of girls at first
= ⁷₁₁ x 297
= 189

Boys who joined : Girls who joined
4 : 3

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

108 + 4 u = 189 + 3 u
4 u - 3 u = 189 - 108

1 u = 81

Number of girls who joined the school in that year
= 3 u
= 3 x 81
= 243

Answer(s): 243