There were 286 children enrolled in the Shannon Gym School in 2020. ³₁₁ of the children were boys. Additional children joined the gym school in 2021. For every 3 boys who joined the gym school, 2 girls joined the gym school. If there was an equal number of girls and boys in 2021, how many girls joined the school in that year?

	Boys	Girls
Before	78	208
Change	+ 3 u	+ 2 u
After	78 + 3 u	208 + 2 u

Fraction of children who are girls
= 1 - ³₁₁
= ⁸₁₁

Number of boys at first
= ³₁₁ x 286
= 78

Number of girls at first
= ⁸₁₁ x 286
= 208

Boys who joined : Girls who joined
3 : 2

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

78 + 3 u = 208 + 2 u
3 u - 2 u = 208 - 78

1 u = 130

Number of girls who joined the school in that year
= 2 u
= 2 x 130
= 260

Answer(s): 260