A box contained black and brown pens. There were 60% more black pens than brown pens. When 11 pens were removed from the box, the amount of black pens decreased by 25% and the amount of brown pens decreased 70%. How many pens were in the box in the end?
| |
Black pens |
Brown pens |
Total pens |
| Before |
8 u |
5 u |
13 u |
| Change |
- 2 u |
- 3.5 u |
- 5.5 u |
| After |
6 u |
1.5 u |
7.5 u |
100% + 60% = 160%
160% =
160100 =
85Number of black pens that were removed from the box
= 25% x 8 u
=
25100 x 8 u
= 2 u
Number of brown pens that were removed from the box
= 70% x 5 u
=
70100 x 5 u
= 3.5 u
Total number of pens that were removed from the box
= 2 u + 3.5 u
= 5.5 u
5.5 u = 11
1 u = 11 ÷ 5.5 = 2
Number of pens in the box in the end
= 6 u + 1.5
= 7.5 u
= 7.5 x 2
= 15
Answer(s): 15
