26 Primary 3 pupils and 20 of Primary 4 pupils went on a school outing. The number of Primary 4 girls was 4 times the number of Primary 3 girls, and there were 18 more Primary 3 boys than Primary 4 boys. How many more Primary 4 girls than Primary 4 boys went on the school outing?
| Primary 3 |
Primary 4 |
| 26 |
20 |
| Girls |
Boys |
Girls |
Boys |
| 1 u |
1 p + 18 |
4 u |
1 p |
Total number of pupils in Primary 3 = 1 u + 1 p + 18
1 u + 1 p + 18 = 26
1 u + 1 p = 26 - 18
1 u + 1 p = 8 --- (1)
Total number of pupils in Primary 4 = 4 u + 1 p
4 u + 1 p = 20 --- (2)
(2) - (1)
(4 u + 1 p) - (1 u + 1 p) = 20 - 8
4 u - 1 u = 12
3 u = 12
1 u = 12 ÷ 3 = 4
Number of girls in Primary 4
= 4 u
= 4 x 4
= 16
Number of boys in Primary 4
= 1 p
= 20 - 4 u
= 20 - 16
= 4
Number of more girls than boys in Primary 4
= 16 - 4
= 12
Answer(s): 12
