The ratio of the number of blue buttons to red buttons is 3 : 1. After Brandon gives away 10 blue buttons and buys another 20 red buttons, there is equal number of blue buttons and red buttons. How many buttons does Brandon have now?
| |
Blue |
Red |
| Before |
3 u |
1 u |
| Change |
- 10 |
+ 20 |
| After |
3 u - 10 |
1 u + 20 |
The number of blue buttons and red buttons in the end is the same.
3 u - 10 = 1 u + 20
3 u - 1 u = 20 + 10
2 u = 30
1 u = 30 ÷ 2 = 15
Number of buttons that Brandon has now
= 3 u - 10 + 1 u + 20
= 3 u + 1 u - 10 + 20
= 4 u + 10
= 4 x 15 + 10
= 60 + 10
= 70
Answer(s): 70
