PSLE
In a school, 70% of the members in Fitness Club and 90% of the members in Reading Club are girls. Both clubs have the same number of boys. The Fitness Club has 80 less girls than the Reading Club. How many members are there in Reading Club?

	Fitness Club		Reading Club
Types	Girls	Boys	Girls	Boys
Comparing the girls and the boys in each club	7x1	3x1	9x3	1x3
Comparing the boys in 2 clubs		1		1
	7 u	3 u	27 u	3 u

70% = ⁷⁰₁₀₀ = ⁷₁₀

Fraction of the members in Fitness Club that are boys
= 1 - ⁷₁₀
= ³₁₀

90% = ⁹⁰₁₀₀ = ⁹₁₀

Fraction of the members in Reading club that are boys
= 1 - ⁹₁₀
= ¹₁₀

The number of boys in both clubs is the same. Make the numerators the same. LCM of 3 and 1 is 3. 

3x110x1 of the members in Fitness Club = 1x310x3 of the members in Reading Club
310of the members in Fitness Club = 330 of the members in Reading Club

Number of less girls in Fitness Club than Reading Club
= 27 u - 7 u
= 20 u

20 u = 80

1 u = 80 ÷ 20 = 4

Number of members in Reading Club
= 30 u
= 30 x 4
= 120

Answer(s): 120