Shannon had some stamp collection.
12 of them were purple and the rest were black. She gave away 121 of the black stamps and 10% of the purple stamps. She then had
25 of her stamp collection left. How many stamps did Shannon give away?
|
Purple |
Black |
Total |
Total |
Before
|
1x5 = 5 u |
1x5 = 5 u |
2x5 = 10 u |
5x2 = 10 u |
Change
|
- 0.1x5 = - 0.5 u |
- 121 |
|
- 3x2 = - 6 u |
After
|
0.9x5 = 4.5 u |
5 u - 121 |
|
2x2 = 4 u |
The total number of stamps that Shannon had at first is repeated. Make the total number of stamps at first the same. LCM 2 and 5 is 10.
Number of purple stamps that Shannon gave away
= 10% x 1 u
=
10100 x 1 u
= 0.1 u
0.5 u - 121 = 6 u
6 u - 0.5 u = 121
5.5 u = 121
1 u = 121 ÷ 5.5 = 22
Number of stamps that Shannon gave away
= 6 u
= 6 x 22
= 132
Answer(s): 132