PSLE
In a school, 30% of the members in Singing Club and 60% of the members in Dancing Club are boys. Both clubs have the same number of girls. The Singing Club has 60 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	3x2	7x2	3x7	2x7
Comparing the girls in 2 clubs		1		1
	6 u	14 u	21 u	14 u

30% = ³⁰₁₀₀ = ³₁₀

Fraction of the members in Singing Club that are girls
= 1 - ³₁₀
= ⁷₁₀

60% = ⁶⁰₁₀₀ = ³₅

Fraction of the members in Dancing club that are girls
= 1 - ³₅
= ²₅

The number of girls in both clubs is the same. Make the numerators the same. LCM of 7 and 2 is 14. 

7x210x2 of the members in Singing Club = 2x75x7 of the members in Dancing Club
1420of the members in Singing Club = 1435 of the members in Dancing Club

Number of less boys in Singing Club than Dancing Club
= 21 u - 6 u
= 15 u

15 u = 60

1 u = 60 ÷ 15 = 4

Number of members in Dancing Club
= 35 u
= 35 x 4
= 140

Answer(s): 140