The ratio of the number of red buttons to blue buttons is 8 : 3. After Harry gives away 10 red buttons and buys another 40 blue buttons, there is equal number of red buttons and blue buttons. How many buttons does Harry have now?
| |
Red |
Blue |
| Before |
8 u |
3 u |
| Change |
- 10 |
+ 40 |
| After |
8 u - 10 |
3 u + 40 |
The number of red buttons and blue buttons in the end is the same.
8 u - 10 = 3 u + 40
8 u - 3 u = 40 + 10
5 u = 50
1 u = 50 ÷ 5 = 10
Number of buttons that Harry has now
= 8 u - 10 + 3 u + 40
= 8 u + 3 u - 10 + 40
= 11 u + 30
= 11 x 10 + 30
= 110 + 30
= 140
Answer(s): 140
