A box contained black and grey erasers. There were 60% more black erasers than grey erasers. When 11 more erasers were poured into the box, the amount of black erasers increased by 25% and the amount of grey erasers increased 70%. How many erasers were in the box at first?
| |
Black erasers |
Grey erasers |
Total erasers |
| Before |
8 u |
5 u |
13 u |
| Change |
+ 2 u |
+ 3.5 u |
+ 5.5 u |
| After |
10 u |
8.5 u |
18.5 u |
100% + 60% = 160%
160% =
160100 =
85Number of more black erasers that were poured into the box
= 25% x 8 u
=
25100 x 8 u
= 2 u
Number of more grey erasers that were poured into the box
= 70% x 5 u
=
70100 x 5 u
= 3.5 u
Total number of more erasers that were poured into the box
= 2 u + 3.5 u
= 5.5 u
5.5 u = 11
1 u = 11 ÷ 5.5 = 2
Number of erasers in the box at first
= 8 u + 5 u
= 13 u
= 13 x 2
= 26
Answer(s): 26
