26 Primary 2 pupils and 21 of Primary 3 pupils went on a school trip. The number of Primary 3 girls was 3 times the number of Primary 2 girls, and there were 13 more Primary 2 boys than Primary 3 boys. How many less Primary 3 boys than Primary 3 girls went on the school trip?
| Primary 2 |
Primary 3 |
| 26 |
21 |
| Girls |
Boys |
Girls |
Boys |
| 1 u |
1 p + 13 |
3 u |
1 p |
Total number of pupils in Primary 2 = 1 u + 1 p + 13
1 u + 1 p + 13 = 26
1 u + 1 p = 26 - 13
1 u + 1 p = 13 --- (1)
Total number of pupils in Primary 3 = 3 u + 1 p
3 u + 1 p = 21 --- (2)
(2) - (1)
(3 u + 1 p) - (1 u + 1 p) = 21 - 13
3 u - 1 u = 8
2 u = 8
1 u = 8 ÷ 2 = 4
Number of girls in Primary 3
= 3 u
= 3 x 4
= 12
Number of boys in Primary 3
= 1 p
= 21 - 3 u
= 21 - 12
= 9
Number of less boys than girls in Primary 3
= 12 - 9
= 3
Answer(s): 3
