125 students went for a singing competition and 67 of them achieved Silver certificates.
35 of the girls and
13 of the boys achieved Silver certificates. How many girls did not achieve Silver certificates?
| Boys |
Girls |
| 5 u |
3 p |
Achieved
Silver |
Did not achieve
Silver |
Achieved
Silver |
Did not achieve
Silver |
| 3 u |
2 u |
1 p |
2 p |
Number of students who did not achieve Silver certificates
= 125 - 67
= 58
3 u + 1 p = 67
1 p = 67 - 3 u --- (1)
2 u + 2 p = 58
2 p = 58 - 2 u --- (2)
Make p the same.
(1)
x22 p = 134 - 6 u --- (3)
(2) = (3)
58 - 2 u = 134 - 6 u
6 u - 2 u = 134 - 58
4 u = 76
1 u = 76 ÷ 4 = 19
Number of boys who did not achieve Silver certificates
= 2 u
= 2 x 19
= 38
Number of girls who did not achieve Silver certificates
= 58 - 38
= 20
Answer(s): 20
