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 7 : 3. The ratio of the number of boys to girls in Team B is 11 : 4. There are 3 times as many pupils in Team B as in Team A. There are 45 less boys in Team A than Team B. What is the total number of pupils in Team A?

Team A		Team B
10 u		15x2 = 30 u
Boys	Girls	Boys	Girls
7 u	3 u	11x2 = 22 u	4x2 = 8 u

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

Total number of pupils in Team B
= 3 x 10 u
= 30 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 30 and 15 is 30.

Number of less boys in Team A than Team B
= 22 u - 7 u
= 15 u

15 u = 45

1 u = 45 ÷ 15 = 3

Total number of pupils in Team A
= 7 u + 3 u
= 10 u
= 10 x 3
= 30

Answer(s): 30