Yoko had some stamp collection.
13 of them were black and the rest were red. She gave away 187 of the red stamps and 10% of the black stamps. She then had
25 of her stamp collection left. How many stamps did Yoko give away?
|
Black |
Red |
Total |
Total |
Before
|
1x5 = 5 u |
2x5 = 10 u |
3x5 = 15 u |
5x3 = 15 u |
Change
|
- 0.1x5 = - 0.5 u |
- 187 |
|
- 3x3 = - 9 u |
After
|
0.9x5 = 4.5 u |
10 u - 187 |
|
2x3 = 6 u |
The total number of stamps that Yoko had at first is repeated. Make the total number of stamps at first the same. LCM 3 and 5 is 15.
Number of black stamps that Yoko gave away
= 10% x 1 u
=
10100 x 1 u
= 0.1 u
0.5 u - 187 = 9 u
9 u - 0.5 u = 187
8.5 u = 187
1 u = 187 ÷ 8.5 = 22
Number of stamps that Yoko gave away
= 9 u
= 9 x 22
= 198
Answer(s): 198