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 4 : 3. The ratio of the number of girls to boys in Team B is 9 : 5. There are 4 times as many contestants in Team B as in Team A. There are 98 more girls in Team B than Team A. What is the total number of boys?

Team A		Team B
7 u		14x2 = 28 u
Girls	Boys	Girls	Boys
4 u	3 u	9x2 = 18 u	5x2 = 10 u

Total number of contestants in Team A
= 4 u + 3 u
= 7 u

Total number of contestants in Team B
= 4 x 7 u
= 28 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 28 and 14 is 28.

Number of more girls in Team B than Team A
= 18 u - 4 u
= 14 u

14 u = 98

1 u = 98 ÷ 14 = 7

Total number of boys
= 3 u + 10 u
= 13 u
= 13 x 7
= 91

Answer(s): 91