There are 139 pupils in a parade square.
38 of the boys and
47 of the girls wear caps, there are 80 pupils in the parade square who do not wear caps. How many girls wear caps?
| |
Boys |
Girls |
Total |
| Do not wear caps |
5 u |
3 p |
80 |
| Wear caps |
3 u |
4 p |
59 |
| Total |
8 u |
7 p |
139 |
Number of pupils who wear caps
= 139 - 80
= 59
5 u + 3 p = 80 --- (1)
3 u + 4 p = 59 --- (2)
Make u the same.
(1)
x 3 15 u + 9 p = 240 --- (3)
(2)
x 5 15 u + 20 p = 295 --- (4)
(4) - (3)
(15 u + 20 p) - (15 u + 9 p) = 295 - 240
20 p - 9 p = 55
11 p = 55
1 p = 55 ÷ 11 = 5
Number of girls who wear caps
= 4 p
= 4 x 5
= 20
Answer(s): 20
