PSLE
In a school, 45% of the members in Reading Club and 50% of the members in Computer Club are boys. Both clubs have the same number of girls. The Computer Club has 8 more boys than the Reading Club. How many boys are there altogether?

	Reading Club		Computer 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 Reading Club that are girls
= 1 - ⁹₂₀
= ¹¹₂₀

50% = ⁵⁰₁₀₀ = ¹₂

Fraction of the members in Computer 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 Reading Club = 1x112x11 of the members in Computer Club
1120of the members in Reading Club = 1122 of the members in Computer Club

Number of more boys in Computer Club than Reading Club
= 11 u - 9 u
= 2 u

2 u = 8

1 u = 8 ÷ 2 = 4

Total number of boys
= 9 u + 11 u
= 20 u
= 20 x 4
= 80

Answer(s): 80