There are 25% more black erasers than grey erasers in a bag. After Zeph removed 20% of the black erasers and increased the number of grey erasers by 20%, there are now 56 fewer black erasers than grey erasers. Find the number of grey erasers at first.
|
Black |
Grey |
Before |
5 u |
4 u |
Change |
- 1 u |
+ 0.8 u |
After |
4 u |
4.8 u |
Number of black erasers in percentage
= 100% + 25%
= 125%
125% =
125100 =
54Number of black erasers that Zeph removed
= 20% x 5 u
=
20100 x 5 u
= 1 u
Number of grey erasers that Zeph increased
= 20% x 4 u
=
20100 x 4 u
= 0.8 u
Number of black erasers in the end
= 5 u - 1 u
= 4 u
Number of grey erasers in the end
= 4 u + 0.8 u
= 4.8 u
Number of fewer black erasers than grey erasers in the end
= 4.8 u - 4 u
= 0.8 u
0.8 u = 56
1 u = 56 ÷ 0.8 = 70
Number of grey erasers at first
= 4 u
= 4 x 70
= 280
Answer(s): 280