Sabrina had some pen collection.
27 of them were silver and the rest were grey. She gave away 101 of the grey pens and 10% of the silver pens. She then had
14 of her pen collection left. How many pens did Sabrina give away?
| |
Silver |
Grey |
Total |
Total |
Before
|
2x4 =
8 u |
5x4 =
20 u |
7x4 =
28 u |
4x7 =
28 u |
Change
|
- 0.2x4 =
- 0.8 u |
- 101 |
|
- 3x7 =
- 21 u |
After
|
1.8x4 =
7.2 u |
20 u - 101 |
|
1x7 =
7 u |
The total number of pens that Sabrina had at first is repeated. Make the total number of pens at first the same. LCM 7 and 4 is 28.
Number of silver pens that Sabrina gave away
= 10% x 2 u
=
10100 x 2 u
= 0.2 u
0.8 u - 101 = 21 u
21 u - 0.8 u = 101
20.2 u = 101
1 u = 101 ÷ 20.2 = 5
Number of pens that Sabrina gave away
= 21 u
= 21 x 5
= 105
Answer(s): 105
