There are 129 pupils in a school field.
38 of the boys and
47 of the girls wear scarves, there are 71 pupils in the school field who do not wear scarves. How many girls wear scarves?
| |
Boys |
Girls |
Total |
| Do not wear scarves |
5 u |
3 p |
71 |
| Wear scarves |
3 u |
4 p |
58 |
| Total |
8 u |
7 p |
129 |
Number of pupils who wear scarves
= 129 - 71
= 58
5 u + 3 p = 71 --- (1)
3 u + 4 p = 58 --- (2)
Make u the same.
(1)
x 3 15 u + 9 p = 213 --- (3)
(2)
x 5 15 u + 20 p = 290 --- (4)
(4) - (3)
(15 u + 20 p) - (15 u + 9 p) = 290 - 213
20 p - 9 p = 77
11 p = 77
1 p = 77 ÷ 11 = 7
Number of girls who wear scarves
= 4 p
= 4 x 7
= 28
Answer(s): 28
