31 Primary 4 pupils and 23 of Primary 5 pupils went on a school learning journey. The number of Primary 5 girls was 3 times the number of Primary 4 girls, and there were 20 more Primary 4 boys than Primary 5 boys. How many more Primary 5 girls than Primary 5 boys went on the school learning journey?
| Primary 4 |
Primary 5 |
| 31 |
23 |
| Girls |
Boys |
Girls |
Boys |
| 1 u |
1 p + 20 |
3 u |
1 p |
Total number of pupils in Primary 4 = 1 u + 1 p + 20
1 u + 1 p + 20 = 31
1 u + 1 p = 31 - 20
1 u + 1 p = 11 --- (1)
Total number of pupils in Primary 5 = 3 u + 1 p
3 u + 1 p = 23 --- (2)
(2) - (1)
(3 u + 1 p) - (1 u + 1 p) = 23 - 11
3 u - 1 u = 12
2 u = 12
1 u = 12 ÷ 2 = 6
Number of girls in Primary 5
= 3 u
= 3 x 6
= 18
Number of boys in Primary 5
= 1 p
= 23 - 3 u
= 23 - 18
= 5
Number of more girls than boys in Primary 5
= 18 - 5
= 13
Answer(s): 13
