PSLE
In a school, 40% of the members in Singing Club and 75% of the members in Dancing Club are boys. Both clubs have the same number of girls. The Singing Club has 49 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	2x1	3x1	3x3	1x3
Comparing the girls in 2 clubs		1		1
	2 u	3 u	9 u	3 u

40% = ⁴⁰₁₀₀ = ²₅

Fraction of the members in Singing Club that are girls
= 1 - ²₅
= ³₅

75% = ⁷⁵₁₀₀ = ³₄

Fraction of the members in Dancing club that are girls
= 1 - ³₄
= ¹₄

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

3x15x1 of the members in Singing Club = 1x34x3 of the members in Dancing Club
35of the members in Singing Club = 312 of the members in Dancing Club

Number of less boys in Singing Club than Dancing Club
= 9 u - 2 u
= 7 u

7 u = 49

1 u = 49 ÷ 7 = 7

Number of members in Dancing Club
= 12 u
= 12 x 7
= 84

Answer(s): 84