Esther baked 80 cupcakes. 25% of them were butter cupcakes. How many more butter cupcakes must Esther bake so that 80% of her cupcakes are butter cupcakes?
| |
Butter cupcakes |
Other cupcakes |
| Before |
25% |
75% |
| Change |
+ ? |
No change |
| After |
80 u |
20 u |
Number of butter cupcakes at first
= 25% x 80
=
25100 x 80
= 20
Percentage of other cupcakes
= 100% - 25%
= 75%
Number of other cupcakes
= 75% x 80
=
75100 x 80
= 60
Number of other cupcakes in the end
= 100 u - 80 u
= 20 u
The number of other cupcakes remains unchanged.
75% = 20 u
20 u = 60
1 u = 60 ÷ 20 = 3
Number of butter cupcakes in the end
= 80 u
= 80 x 3
= 240
Additional number of butter cupcakes that Esther must bake
= 240 - 20
= 220
Answer(s): 220
