31 Primary 2 students and 23 of Primary 3 students went on a school learning journey. The number of Primary 3 boys was 4 times the number of Primary 2 boys, and there were 20 more Primary 2 girls than Primary 3 girls. How many more Primary 3 boys than Primary 3 girls went on the school learning journey?
| Primary 2 |
Primary 3 |
| 31 |
23 |
| Boys |
Girls |
Boys |
Girls |
| 1 u |
1 p + 20 |
4 u |
1 p |
Total number of students in Primary 2 = 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 students in Primary 3 = 4 u + 1 p
4 u + 1 p = 23 --- (2)
(2) - (1)
(4 u + 1 p) - (1 u + 1 p) = 23 - 11
4 u - 1 u = 12
3 u = 12
1 u = 12 ÷ 3 = 4
Number of boys in Primary 3
= 4 u
= 4 x 4
= 16
Number of girls in Primary 3
= 1 p
= 23 - 4 u
= 23 - 16
= 7
Number of more boys than girls in Primary 3
= 16 - 7
= 9
Answer(s): 9
