26 Primary 5 students and 23 of Primary 6 students went on a school oversea trip. The number of Primary 6 girls was 4 times the number of Primary 5 girls, and there were 18 more Primary 5 boys than Primary 6 boys. How many less Primary 6 boys than Primary 6 girls went on the school oversea trip?
| Primary 5 |
Primary 6 |
| 26 |
23 |
| Girls |
Boys |
Girls |
Boys |
| 1 u |
1 p + 18 |
4 u |
1 p |
Total number of students in Primary 5 = 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 students in Primary 6 = 4 u + 1 p
4 u + 1 p = 23 --- (2)
(2) - (1)
(4 u + 1 p) - (1 u + 1 p) = 23 - 8
4 u - 1 u = 15
3 u = 15
1 u = 15 ÷ 3 = 5
Number of girls in Primary 6
= 4 u
= 4 x 5
= 20
Number of boys in Primary 6
= 1 p
= 23 - 4 u
= 23 - 20
= 3
Number of less boys than girls in Primary 6
= 20 - 3
= 17
Answer(s): 17
