The ratio of the number of red stamps to green stamps is 7 : 2. After Flynn gives away 60 red stamps and buys another 90 green stamps, there is equal number of red stamps and green stamps. How many stamps does Flynn have now?
| |
Red |
Green |
| Before |
7 u |
2 u |
| Change |
- 60 |
+ 90 |
| After |
7 u - 60 |
2 u + 90 |
The number of red stamps and green stamps in the end is the same.
7 u - 60 = 2 u + 90
7 u - 2 u = 90 + 60
5 u = 150
1 u = 150 ÷ 5 = 30
Number of stamps that Flynn has now
= 7 u - 60 + 2 u + 90
= 7 u + 2 u - 60 + 90
= 9 u + 30
= 9 x 30 + 30
= 270 + 30
= 300
Answer(s): 300
