145 pupils went for a spelling test and 59 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 pupils who did not achieve Bronze certificates
= 145 - 59
= 86
3 u + 1 p = 59
1 p = 59 - 3 u --- (1)
2 u + 3 p = 86
3 p = 86 - 2 u --- (2)
Make p the same.
(1)
x33 p = 177 - 9 u --- (3)
(2) = (3)
86 - 2 u = 177 - 9 u
9 u - 2 u = 177 - 86
7 u = 91
1 u = 91 ÷ 7 = 13
Number of boys who achieved Bronze certificates
= 3 u
= 3 x 13
= 39
Number of girls who achieved Bronze certificates
= 59 - 39
= 20
Answer(s): 20