PSLE
The contestants at a contest are divided in Team A and Team B. The ratio of the number of girls to boys in Team A is 7 : 3. The ratio of the number of girls to boys in Team B is 3 : 1. There are 2 times as many contestants in Team B as in Team A. There are 32 more girls in Team B than Team A. What is the total number of boys?

Team A		Team B
10 u		4x5 = 20 u
Girls	Boys	Girls	Boys
7 u	3 u	3x5 = 15 u	1x5 = 5 u

Total number of contestants in Team A
= 7 u + 3 u
= 10 u

Total number of contestants in Team B
= 2 x 10 u
= 20 u

The total number of contestants in Team B is repeated.
Use LCM to make the total number of contestants in Team B the same.
LCM of 20 and 4 is 20.

Number of more girls in Team B than Team A
= 15 u - 7 u
= 8 u

8 u = 32

1 u = 32 ÷ 8 = 4

Total number of boys
= 3 u + 5 u
= 8 u
= 8 x 4
= 32

Answer(s): 32