27 Primary 5 pupils and 24 of Primary 6 pupils went on a school oversea trip. The number of Primary 6 boys was 3 times the number of Primary 5 boys, and there were 13 more Primary 5 girls than Primary 6 girls. How many less Primary 6 girls than Primary 6 boys went on the school oversea trip?
| Primary 5 |
Primary 6 |
| 27 |
24 |
| Boys |
Girls |
Boys |
Girls |
| 1 u |
1 p + 13 |
3 u |
1 p |
Total number of pupils in Primary 5 = 1 u + 1 p + 13
1 u + 1 p + 13 = 27
1 u + 1 p = 27 - 13
1 u + 1 p = 14 --- (1)
Total number of pupils in Primary 6 = 3 u + 1 p
3 u + 1 p = 24 --- (2)
(2) - (1)
(3 u + 1 p) - (1 u + 1 p) = 24 - 14
3 u - 1 u = 10
2 u = 10
1 u = 10 ÷ 2 = 5
Number of boys in Primary 6
= 3 u
= 3 x 5
= 15
Number of girls in Primary 6
= 1 p
= 24 - 3 u
= 24 - 15
= 9
Number of less girls than boys in Primary 6
= 15 - 9
= 6
Answer(s): 6
