The ratio of the number of green stamps to blue stamps is 9 : 5. After Simon gives away 10 green stamps and buys another 30 blue stamps, there is equal number of green stamps and blue stamps. How many stamps does Simon have now?
| |
Green |
Blue |
| Before |
9 u |
5 u |
| Change |
- 10 |
+ 30 |
| After |
9 u - 10 |
5 u + 30 |
The number of green stamps and blue stamps in the end is the same.
9 u - 10 = 5 u + 30
9 u - 5 u = 30 + 10
4 u = 40
1 u = 40 ÷ 4 = 10
Number of stamps that Simon has now
= 9 u - 10 + 5 u + 30
= 9 u + 5 u - 10 + 30
= 14 u + 20
= 14 x 10 + 20
= 140 + 20
= 160
Answer(s): 160
