The ratio of the number of blue stamps to green stamps is 8 : 5. After Oliver gives away 70 blue stamps and buys another 80 green stamps, there is equal number of blue stamps and green stamps. How many stamps does Oliver have now?
| |
Blue |
Green |
| Before |
8 u |
5 u |
| Change |
- 70 |
+ 80 |
| After |
8 u - 70 |
5 u + 80 |
The number of blue stamps and green stamps in the end is the same.
8 u - 70 = 5 u + 80
8 u - 5 u = 80 + 70
3 u = 150
1 u = 150 ÷ 3 = 50
Number of stamps that Oliver has now
= 8 u - 70 + 5 u + 80
= 8 u + 5 u - 70 + 80
= 13 u + 10
= 13 x 50 + 10
= 650 + 10
= 660
Answer(s): 660
