The ratio of the number of red stamps to green stamps is 5 : 3. After Harry gives away 30 red stamps and buys another 80 green stamps, there is equal number of red stamps and green stamps. How many stamps does Harry have now?
| |
Red |
Green |
| Before |
5 u |
3 u |
| Change |
- 30 |
+ 80 |
| After |
5 u - 30 |
3 u + 80 |
The number of red stamps and green stamps in the end is the same.
5 u - 30 = 3 u + 80
5 u - 3 u = 80 + 30
2 u = 110
1 u = 110 ÷ 2 = 55
Number of stamps that Harry has now
= 5 u - 30 + 3 u + 80
= 5 u + 3 u - 30 + 80
= 8 u + 50
= 8 x 55 + 50
= 440 + 50
= 490
Answer(s): 490
