12 days ago, Tina had a total of 150 pink and red erasers. 20% of her erasers were red erasers. Today, her father gave her some more erasers. As a result, her pink erasers increased by 10%. Now, 50% of her erasers are red erasers. How many red erasers did her father give her?
| |
Red erasers |
Pink erasers |
Total
erasers |
| Before |
1 u |
4 u |
150 |
| Change |
+ 3.4 u |
+ 0.4 u |
|
| After |
4.4 u |
4.4 u |
|
Comparing the
pink erasers and
red erasers in the end |
1 |
1 |
|
20% =
20100 =
15 Red erasers : Pink erasers = 1 : 4
Increase in the number of pink erasers
= 10% x 4 u
=
10100 x 4 u
= 0.4 u
50% =
50100 =
12 In the end
Red erasers : Pink erasers = 1 : 1
Number of erasers at first
= 4 u + 1 u
= 5 u
5 u = 150
1 u = 150 ÷ 5 = 30
Number of red erasers that Tina received from her father
= 4.4 u - 1 u
= 3.4 u
= 3.4 x 30
= 102
Answer(s): 102
