122 adults are in a school.
13 of the women and
15 of the men wear glasses.
34 adults wear glasses.
- How many women are there?
- How many men are there?
- How many adults do not wear glasses?
|
Number |
Women |
Men |
Total |
122 |
3 u |
5 p |
Wear glasses |
34 |
1 u |
1 p |
No glasses |
|
2 u |
4 p |
(a)
Number of women = 3 u
Number of men = 5 p
3 u + 5 p = 122 --- (1)
1 u + 1 p = 34 --- (2)
(2)
x 3 3 u + 3 p = 102 --- (3)
(1) - (3)
(3 u + 5 p) - (3 u + 3 p) = 122 - 102
3 u + 5 p - 3 u - 3 p = 20
2 p = 20
1 p = 20 ÷ 2 = 10
Substitute 1 p = 10 into (2).
1 u + 1 p = 34
1 u + 10 = 34
1 u = 34 - 10 = 24
Number of women
= 3 u
= 3 x 24
= 72
(b)
Number of men
= 5 p
= 5 x 10
= 50
(c)
Number of women who do not wear glasses
= 3 u - 1 u
= 2 u
Number of men who do not wear glasses
= 5 p - 1 p
= 4 p
Number of adults who do not wear glasses
= 122 - 34
= 88
Answer(s): (a) 72; (b) 50; (c) 88