PSLE
In a school, 40% of the members in Computer Club and 75% of the members in Art Club are boys. Both clubs have the same number of girls. The Art Club has 56 more boys than the Computer Club. How many boys are there altogether?

	Computer Club		Art 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 Computer Club that are girls
= 1 - ²₅
= ³₅

75% = ⁷⁵₁₀₀ = ³₄

Fraction of the members in Art 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 Computer Club = 1x34x3 of the members in Art Club
35of the members in Computer Club = 312 of the members in Art Club

Number of more boys in Art Club than Computer Club
= 9 u - 2 u
= 7 u

7 u = 56

1 u = 56 ÷ 7 = 8

Total number of boys
= 2 u + 9 u
= 11 u
= 11 x 8
= 88

Answer(s): 88