25 Primary 2 students and 22 of Primary 3 students went on a school trip. The number of Primary 3 girls was 5 times the number of Primary 2 girls, and there were 19 less Primary 3 boys than Primary 2 boys. How many less Primary 3 boys than Primary 3 girls went on the school trip?
| Primary 2 |
Primary 3 |
| 25 |
22 |
| Girls |
Boys |
Girls |
Boys |
| 1 u |
1 p + 19 |
5 u |
1 p |
Total number of students in Primary 2 = 1 u + 1 p + 19
1 u + 1 p + 19 = 25
1 u + 1 p = 25 - 19
1 u + 1 p = 6 --- (1)
Total number of students in Primary 3 = 5 u + 1 p
5 u + 1 p = 22 --- (2)
(2) - (1)
(5 u + 1 p) - (1 u + 1 p) = 22 - 6
5 u - 1 u = 16
4 u = 16
1 u = 16 ÷ 4 = 4
Number of girls in Primary 3
= 5 u
= 5 x 4
= 20
Number of boys in Primary 3
= 1 p
= 22 - 5 u
= 22 - 20
= 2
Number of less boys than girls in Primary 3
= 20 - 2
= 18
Answer(s): 18
