The ratio of the number of green stamps to red stamps is 8 : 3. After Oscar gives away 40 green stamps and buys another 60 red stamps, there is equal number of green stamps and red stamps. How many stamps does Oscar have now?
| |
Green |
Red |
| Before |
8 u |
3 u |
| Change |
- 40 |
+ 60 |
| After |
8 u - 40 |
3 u + 60 |
The number of green stamps and red stamps in the end is the same.
8 u - 40 = 3 u + 60
8 u - 3 u = 60 + 40
5 u = 100
1 u = 100 ÷ 5 = 20
Number of stamps that Oscar has now
= 8 u - 40 + 3 u + 60
= 8 u + 3 u - 40 + 60
= 11 u + 20
= 11 x 20 + 20
= 220 + 20
= 240
Answer(s): 240
