165 students went for a dancing competition and 61 of them achieved Silver certificates.
35 of the boys and
15 of the girls achieved Silver certificates. How many boys did not achieve Silver certificates?
| Girls |
Boys |
| 5 u |
5 p |
Achieved
Silver |
Did not achieve
Silver |
Achieved
Silver |
Did not achieve
Silver |
| 3 u |
2 u |
1 p |
4 p |
Number of students who did not achieve Silver certificates
= 165 - 61
= 104
3 u + 1 p = 61
1 p = 61 - 3 u --- (1)
2 u + 4 p = 104
4 p = 104 - 2 u --- (2)
Make p the same.
(1)
x44 p = 244 - 12 u --- (3)
(2) = (3)
104 - 2 u = 244 - 12 u
12 u - 2 u = 244 - 104
10 u = 140
1 u = 140 ÷ 10 = 14
Number of girls who achieved Silver certificates
= 3 u
= 3 x 14
= 42
Number of boys who achieved Silver certificates
= 61 - 42
= 19
Answer(s): 19
