PSLE
In a school, 40% of the members in Fitness Club and 45% of the members in Reading Club are girls. Both clubs have the same number of boys. The Reading Club has 20 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	2x11	3x11	9x3	11x3
Comparing the boys in 2 clubs		1		1
	22 u	33 u	27 u	33 u

40% = ⁴⁰₁₀₀ = ²₅

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

45% = ⁴⁵₁₀₀ = ⁹₂₀

Fraction of the members in Reading club that are boys
= 1 - ⁹₂₀
= ¹¹₂₀

The number of boys in both clubs is the same. Make the numerators the same. LCM of 3 and 11 is 33. 

3x115x11 of the members in Fitness Club = 11x320x3 of the members in Reading Club
3355of the members in Fitness Club = 3360 of the members in Reading Club

Number of more girls in Reading Club than Fitness Club
= 27 u - 22 u
= 5 u

5 u = 20

1 u = 20 ÷ 5 = 4

Total number of girls
= 22 u + 27 u
= 49 u
= 49 x 4
= 196

Answer(s): 196