On a shelf, there were 150 shirts and sweaters. Ethan spilt coffee on the shelf and stained 50% of the sweaters and 10% of the shirts. If 119 shirts and sweaters were still clean, how many clean sweaters were there?
| |
Shirts |
Sweaters |
Total |
| Stained |
1 u |
1 p |
31 |
| Clean |
9 u |
1 p |
119 |
| Total |
10 u |
2 p |
150 |
50% =
50100 =
12 10% =
10100 =
110 Number of stained clothes
= 150 - 119
= 31
9 u + 1 p = 119
1 p = 119 - 9 u --- (1)
1 u + 1 p = 31
1 p = 31 - 1 u --- (2)
(2) - (1)
31 - 1 u = 119 - 9 u
9 u - 1 u = 119 - 31
8 u = 88
1 u = 88 ÷ 8 = 11
Number of clean sweaters is the same as the number of stained sweaters.
Number of clean sweaters
= 31 - 1 u
= 31 - 11
= 20
Answer(s): 20
