PSLE
The contestants at a contest are divided in Team A and Team B. The ratio of the number of boys to girls in Team A is 7 : 1. The ratio of the number of boys to girls in Team B is 5 : 7. There are 3 times as many contestants in Team B as in Team A. There are 6 more boys in Team B than Team A. What is the total number of girls?

Team A		Team B
8 u		12x2 = 24 u
Boys	Girls	Boys	Girls
7 u	1 u	5x2 = 10 u	7x2 = 14 u

Total number of contestants in Team A
= 7 u + 1 u
= 8 u

Total number of contestants in Team B
= 3 x 8 u
= 24 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 24 and 12 is 24.

Number of more boys in Team B than Team A
= 10 u - 7 u
= 3 u

3 u = 6

1 u = 6 ÷ 3 = 2

Total number of girls
= 1 u + 14 u
= 15 u
= 15 x 2
= 30

Answer(s): 30