PSLE
In a school, 45% of the members in Singing Club and 50% of the members in Dancing Club are boys. Both clubs have the same number of girls. The Singing Club has 4 less boys than the Dancing Club. How many members are there in Dancing Club?

	Singing Club		Dancing Club
Types	Boys	Girls	Boys	Girls
Comparing the boys and the girls in each club	9x1	11x1	1x11	1x11
Comparing the girls in 2 clubs		1		1
	9 u	11 u	11 u	11 u

45% = ⁴⁵₁₀₀ = ⁹₂₀

Fraction of the members in Singing Club that are girls
= 1 - ⁹₂₀
= ¹¹₂₀

50% = ⁵⁰₁₀₀ = ¹₂

Fraction of the members in Dancing club that are girls
= 1 - ¹₂
= ¹₂

The number of girls in both clubs is the same. Make the numerators the same. LCM of 11 and 1 is 11. 

11x120x1 of the members in Singing Club = 1x112x11 of the members in Dancing Club
1120of the members in Singing Club = 1122 of the members in Dancing Club

Number of less boys in Singing Club than Dancing Club
= 11 u - 9 u
= 2 u

2 u = 4

1 u = 4 ÷ 2 = 2

Number of members in Dancing Club
= 22 u
= 22 x 2
= 44

Answer(s): 44