²₉ of the visitors at a stadium were boys. 75% of the remaining visitors were girls and the rest were adults. The number of girls was 120 more than the total number of boys and adults. After some girls left the stadium, 50% of the visitors that remained were girls. How many girls left the stadium?

Boys	Adults	Girls	Total
2x4	7x4		9x4
	1x7	3x7
8	7	21	36

	Boys and adults	Girls
Before	15x1 = 15 u	21x1 = 21 u
Change		- 6 u
After	1x15 = 15 u	1x15 = 15 u

75% = ⁷⁵₁₀₀ = ³₄
Adults : Girls = 1 : 3

The total number of adults and girls at first is repeated.  Make the total number of adults at first the same. LCM of 7 and 4 is 28.

50% = ⁵⁰₁₀₀ = ¹₂

When some girls left, the total number of boys and adults remains unchanged. Make the total number of boys and adults the same. LCM of 15 and 1 is 15.

The number of girls was 120 more than the total number of boys and adults at first.

Number of more girls than the total number of boys and adults at first
= 21 u - 15 u
= 6 u

6 u = 120

1 u = 120 ÷ 6 = 20

Number of girls who left the stadium
= 21 u - 15 u
= 6 u
= 6 x 20
= 120

Answer(s): 120