120 pupils went for a dancing competition and 39 of them achieved Bronze certificates.
25 of the girls and
14 of the boys achieved Bronze certificates. How many girls did not achieve Bronze certificates?
| Boys |
Girls |
| 5 u |
4 p |
Achieved
Bronze |
Did not achieve
Bronze |
Achieved
Bronze |
Did not achieve
Bronze |
| 2 u |
3 u |
1 p |
3 p |
Number of pupils who did not achieve Bronze certificates
= 120 - 39
= 81
2 u + 1 p = 39
1 p = 39 - 2 u --- (1)
3 u + 3 p = 81
3 p = 81 - 3 u --- (2)
Make p the same.
(1)
x33 p = 117 - 6 u --- (3)
(2) = (3)
81 - 3 u = 117 - 6 u
6 u - 3 u = 117 - 81
3 u = 36
1 u = 36 ÷ 3 = 12
Number of boys who did not achieve Bronze certificates
= 3 u
= 3 x 12
= 36
Number of girls who did not achieve Bronze certificates
= 81 - 36
= 45
Answer(s): 45
