24 Primary 1 pupils and 21 of Primary 2 pupils went on a school trip. The number of Primary 2 boys was 5 times the number of Primary 1 boys, and there were 19 more Primary 1 girls than Primary 2 girls. How many less Primary 2 girls than Primary 2 boys went on the school trip?
| Primary 1 |
Primary 2 |
| 24 |
21 |
| Boys |
Girls |
Boys |
Girls |
| 1 u |
1 p + 19 |
5 u |
1 p |
Total number of pupils in Primary 1 = 1 u + 1 p + 19
1 u + 1 p + 19 = 24
1 u + 1 p = 24 - 19
1 u + 1 p = 5 --- (1)
Total number of pupils in Primary 2 = 5 u + 1 p
5 u + 1 p = 21 --- (2)
(2) - (1)
(5 u + 1 p) - (1 u + 1 p) = 21 - 5
5 u - 1 u = 16
4 u = 16
1 u = 16 ÷ 4 = 4
Number of boys in Primary 2
= 5 u
= 5 x 4
= 20
Number of girls in Primary 2
= 1 p
= 21 - 5 u
= 21 - 20
= 1
Number of less girls than boys in Primary 2
= 20 - 1
= 19
Answer(s): 19
