172 students went for a singing competition and 78 of them achieved Bronze certificates.
35 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 |
| 3 u |
2 u |
1 p |
3 p |
Number of students who did not achieve Bronze certificates
= 172 - 78
= 94
3 u + 1 p = 78
1 p = 78 - 3 u --- (1)
2 u + 3 p = 94
3 p = 94 - 2 u --- (2)
Make p the same.
(1)
x33 p = 234 - 9 u --- (3)
(2) = (3)
94 - 2 u = 234 - 9 u
9 u - 2 u = 234 - 94
7 u = 140
1 u = 140 ÷ 7 = 20
Number of boys who achieved Bronze certificates
= 3 u
= 3 x 20
= 60
Number of girls who achieved Bronze certificates
= 78 - 60
= 18
Answer(s): 18
