PSLE
In a school, 40% of the members in Fitness Club and 80% of the members in Reading Club are girls. Both clubs have the same number of boys. The Reading Club has 120 more girls than the Fitness Club. How many girls are there altogether?

	Fitness Club		Reading Club
Types	Girls	Boys	Girls	Boys
Comparing the girls and the boys in each club	2x1	3x1	4x3	1x3
Comparing the boys in 2 clubs		1		1
	2 u	3 u	12 u	3 u

40% = ⁴⁰₁₀₀ = ²₅

Fraction of the members in Fitness Club that are boys
= 1 - ²₅
= ³₅

80% = ⁸⁰₁₀₀ = ⁴₅

Fraction of the members in Reading club that are boys
= 1 - ⁴₅
= ¹₅

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

3x15x1 of the members in Fitness Club = 1x35x3 of the members in Reading Club
35of the members in Fitness Club = 315 of the members in Reading Club

Number of more girls in Reading Club than Fitness Club
= 12 u - 2 u
= 10 u

10 u = 120

1 u = 120 ÷ 10 = 12

Total number of girls
= 2 u + 12 u
= 14 u
= 14 x 12
= 168

Answer(s): 168