The ratio of the number of blue stamps to green stamps is 7 : 3. After Caden gives away 50 blue stamps and buys another 90 green stamps, there is equal number of blue stamps and green stamps. How many stamps does Caden have now?
| |
Blue |
Green |
| Before |
7 u |
3 u |
| Change |
- 50 |
+ 90 |
| After |
7 u - 50 |
3 u + 90 |
The number of blue stamps and green stamps in the end is the same.
7 u - 50 = 3 u + 90
7 u - 3 u = 90 + 50
4 u = 140
1 u = 140 ÷ 4 = 35
Number of stamps that Caden has now
= 7 u - 50 + 3 u + 90
= 7 u + 3 u - 50 + 90
= 10 u + 40
= 10 x 35 + 40
= 350 + 40
= 390
Answer(s): 390
