7 days ago, Betty had a total of 200 gold and purple pens. 25% of her pens were purple pens. Today, her mother gave her some more pens. As a result, her gold pens increased by 30%. Now, 50% of her pens are purple pens. How many purple pens did her mother give her?
| |
Purple pens |
Gold pens |
Total
pens |
| Before |
1 u |
3 u |
200 |
| Change |
+ 2.9 u |
+ 0.9 u |
|
| After |
3.9 u |
3.9 u |
|
Comparing the
gold pens and
purple pens in the end |
1 |
1 |
|
25% =
25100 =
14 Purple pens : Gold pens = 1 : 3
Increase in the number of gold pens
= 30% x 3 u
=
30100 x 3 u
= 0.9 u
50% =
50100 =
12 In the end
Purple pens : Gold pens = 1 : 1
Number of pens at first
= 3 u + 1 u
= 4 u
4 u = 200
1 u = 200 ÷ 4 = 50
Number of purple pens that Betty received from her mother
= 3.9 u - 1 u
= 2.9 u
= 2.9 x 50
= 145
Answer(s): 145
