The ratio of the number of green stamps to red stamps is 7 : 5. After Xavier gives away 70 green stamps and buys another 90 red stamps, there is equal number of green stamps and red stamps. How many stamps does Xavier have now?
| |
Green |
Red |
| Before |
7 u |
5 u |
| Change |
- 70 |
+ 90 |
| After |
7 u - 70 |
5 u + 90 |
The number of green stamps and red stamps in the end is the same.
7 u - 70 = 5 u + 90
7 u - 5 u = 90 + 70
2 u = 160
1 u = 160 ÷ 2 = 80
Number of stamps that Xavier has now
= 7 u - 70 + 5 u + 90
= 7 u + 5 u - 70 + 90
= 12 u + 20
= 12 x 80 + 20
= 960 + 20
= 980
Answer(s): 980
