10% of the people are performers for a concert and the rest are spectators. 70% of the spectators are children and there are 1440 more child spectators than adult spectators. How many child spectators must leave so that 26% of the people are child spectators?

	Performers	Spectators
	1x10	9x10
		Adults	Children
		3x9	7x9
Before	10 u	27 u	63 u
Change			- ?
After	37x1 = 37 u		13x1 =  13 u

10% = ¹⁰₁₀₀ = ¹₁₀ 

70% = ⁷⁰₁₀₀ = ⁷₁₀ 

26% = ²⁶₁₀₀ = ¹³₅₀

The total number of spectators at first is repeated.  Make the total number of spectators the same.  LCM of 9 and 10 is 90.

Number of more child spectators than adult spectators at first
= 63 u - 27 u
= 36 u

36 u = 1440

1 u = 1440 ÷ 36 = 40

If some child spectators leave, the total number of adult spectators and performers remains unchanged.  

Number of child spectators who must leave so that 26% of the people are child spectators
= 63 u - 13 u
= 50 u
= 50 x 40
= 2000

Answer(s): 2000