2 days ago, Penelope had a total of 275 red and purple erasers. 40% of her erasers were purple erasers. Today, her older brother gave her some more erasers. As a result, her red erasers increased by 20%. Now, 50% of her erasers are purple erasers. How many purple erasers did her older brother give her?
| |
Purple erasers |
Red erasers |
Total
erasers |
| Before |
2 u |
3 u |
275 |
| Change |
+ 1.6 u |
+ 0.6 u |
|
| After |
3.6 u |
3.6 u |
|
Comparing the
red erasers and
purple erasers in the end |
1 |
1 |
|
40% =
40100 =
25 Purple erasers : Red erasers = 2 : 3
Increase in the number of red erasers
= 20% x 3 u
=
20100 x 3 u
= 0.6 u
50% =
50100 =
12 In the end
Purple erasers : Red erasers = 1 : 1
Number of erasers at first
= 3 u + 2 u
= 5 u
5 u = 275
1 u = 275 ÷ 5 = 55
Number of purple erasers that Penelope received from her older brother
= 3.6 u - 2 u
= 1.6 u
= 1.6 x 55
= 88
Answer(s): 88
