PSLE
The pupils at a school choir are divided in Team A and Team B. The ratio of the number of boys to girls in Team A is 4 : 3. The ratio of the number of boys to girls in Team B is 9 : 5. There are 4 times as many pupils in Team B as in Team A. There are 140 more boys in Team B than Team A. What is the total number of girls?

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

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

Total number of pupils in Team B
= 4 x 7 u
= 28 u

The total number of pupils in Team B is repeated.
Use LCM to make the total number of pupils in Team B the same.
LCM of 28 and 14 is 28.

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

14 u = 140

1 u = 140 ÷ 14 = 10

Total number of girls
= 3 u + 10 u
= 13 u
= 13 x 10
= 130

Answer(s): 130