13 days ago, Sabrina had a total of 300 brown and grey erasers. 40% of her erasers were grey erasers. Today, her auntie gave her some more erasers. As a result, her brown erasers increased by 10%. Now, 50% of her erasers are grey erasers. How many grey erasers did her auntie give her?
| |
Grey erasers |
Brown erasers |
Total
erasers |
| Before |
2 u |
3 u |
300 |
| Change |
+ 1.3 u |
+ 0.3 u |
|
| After |
3.3 u |
3.3 u |
|
Comparing the
brown erasers and
grey erasers in the end |
1 |
1 |
|
40% =
40100 =
25 Grey erasers : Brown erasers = 2 : 3
Increase in the number of brown erasers
= 10% x 3 u
=
10100 x 3 u
= 0.3 u
50% =
50100 =
12 In the end
Grey erasers : Brown erasers = 1 : 1
Number of erasers at first
= 3 u + 2 u
= 5 u
5 u = 300
1 u = 300 ÷ 5 = 60
Number of grey erasers that Sabrina received from her auntie
= 3.3 u - 2 u
= 1.3 u
= 1.3 x 60
= 78
Answer(s): 78
