13 days ago, Joelle had a total of 300 black and yellow buttons. 25% of her buttons were yellow buttons. Today, her cousin gave her some more buttons. As a result, her black buttons increased by 40%. Now, 50% of her buttons are yellow buttons. How many yellow buttons did her cousin give her?
| |
Yellow buttons |
Black buttons |
Total
buttons |
| Before |
1 u |
3 u |
300 |
| Change |
+ 3.2 u |
+ 1.2 u |
|
| After |
4.2 u |
4.2 u |
|
Comparing the
black buttons and
yellow buttons in the end |
1 |
1 |
|
25% =
25100 =
14 Yellow buttons : Black buttons = 1 : 3
Increase in the number of black buttons
= 40% x 3 u
=
40100 x 3 u
= 1.2 u
50% =
50100 =
12 In the end
Yellow buttons : Black buttons = 1 : 1
Number of buttons at first
= 3 u + 1 u
= 4 u
4 u = 300
1 u = 300 ÷ 4 = 75
Number of yellow buttons that Joelle received from her cousin
= 4.2 u - 1 u
= 3.2 u
= 3.2 x 75
= 240
Answer(s): 240
