On a shelf, there were 99 sweaters and cardigans. Andy spilt hot coffee on the shelf and stained 50% of the cardigans and 20% of the sweaters. If 78 sweaters and cardigans were still clean, how many stained cardigans were there?
| |
Sweaters |
Cardigans |
Total |
| Stained |
1 u |
1 p |
21 |
| Clean |
4 u |
1 p |
78 |
| Total |
5 u |
2 p |
99 |
50% =
50100 =
12 20% =
20100 =
15 Number of stained clothes
= 99 - 78
= 21
4 u + 1 p = 78
1 p = 78 - 4 u --- (1)
1 u + 1 p = 21
1 p = 21 - 1 u --- (2)
(2) - (1)
21 - 1 u = 78 - 4 u
4 u - 1 u = 78 - 21
3 u = 57
1 u = 57 ÷ 3 = 19
Number of stained cardigans
= 21 - 1 u
= 21 - 19
= 2
Answer(s): 2
