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 2 : 1. The ratio of the number of boys to girls in Team B is 5 : 1. There are 4 times as many contestants in Team B as in Team A. There are 72 more boys in Team B than Team A. What is the total number of contestants?

Team A		Team B
3 u		6x2 = 12 u
Boys	Girls	Boys	Girls
2 u	1 u	5x2 = 10 u	1x2 = 2 u

Total number of contestants in Team A
= 2 u + 1 u
= 3 u

Total number of contestants in Team B
= 4 x 3 u
= 12 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 12 and 6 is 12.

Number of more boys in Team B than Team A
= 10 u - 2 u
= 8 u

8 u = 72

1 u = 72 ÷ 8 = 9

Total number of contestants
= 2 u + 1 u + 10 u + 2 u
= 15 u
= 15 x 9
= 135

Answer(s): 135