15 days ago, Pamela had a total of 200 red and yellow buttons. 40% of her buttons were yellow buttons. Today, her mother gave her some more buttons. As a result, her red buttons increased by 25%. Now, 50% of her buttons are yellow buttons. How many yellow buttons did her mother give her?
| |
Yellow buttons |
Red buttons |
Total
buttons |
| Before |
2 u |
3 u |
200 |
| Change |
+ 1.75 u |
+ 0.75 u |
|
| After |
3.75 u |
3.75 u |
|
Comparing the
red buttons and
yellow buttons in the end |
1 |
1 |
|
40% =
40100 =
25 Yellow buttons : Red buttons = 2 : 3
Increase in the number of red buttons
= 25% x 3 u
=
25100 x 3 u
= 0.75 u
50% =
50100 =
12 In the end
Yellow buttons : Red buttons = 1 : 1
Number of buttons at first
= 3 u + 2 u
= 5 u
5 u = 200
1 u = 200 ÷ 5 = 40
Number of yellow buttons that Pamela received from her mother
= 3.75 u - 2 u
= 1.75 u
= 1.75 x 40
= 70
Answer(s): 70
