There were 176 children enrolled in the Shiyun Acting School in 2019. ⁴₁₁ of the children were girls. Additional children joined the acting school in 2020. For every 4 girls who joined the acting school, 3 boys joined the acting school. If there was an equal number of boys and girls in 2020, how many boys joined the school in that year?

	Girls	Boys
Before	64	112
Change	+ 4 u	+ 3 u
After	64 + 4 u	112 + 3 u

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

Number of girls at first
= ⁴₁₁ x 176
= 64

Number of boys at first
= ⁷₁₁ x 176
= 112

Girls who joined : Boys who joined
4 : 3

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

64 + 4 u = 112 + 3 u
4 u - 3 u = 112 - 64

1 u = 48

Number of boys who joined the school in that year
= 3 u
= 3 x 48
= 144

Answer(s): 144