The ratio of the number of blue buttons to green buttons is 9 : 4. After Eric gives away 30 blue buttons and buys another 70 green buttons, there is equal number of blue buttons and green buttons. How many buttons does Eric have now?
| |
Blue |
Green |
| Before |
9 u |
4 u |
| Change |
- 30 |
+ 70 |
| After |
9 u - 30 |
4 u + 70 |
The number of blue buttons and green buttons in the end is the same.
9 u - 30 = 4 u + 70
9 u - 4 u = 70 + 30
5 u = 100
1 u = 100 ÷ 5 = 20
Number of buttons that Eric has now
= 9 u - 30 + 4 u + 70
= 9 u + 4 u - 30 + 70
= 13 u + 40
= 13 x 20 + 40
= 260 + 40
= 300
Answer(s): 300
