The ratio of the number of blue stamps to red stamps is 9 : 4. After Wesley gives away 20 blue stamps and buys another 80 red stamps, there is equal number of blue stamps and red stamps. How many stamps does Wesley have now?
|
Blue |
Red |
Before |
9 u |
4 u |
Change |
- 20 |
+ 80 |
After |
9 u - 20 |
4 u + 80 |
The number of blue stamps and red stamps in the end is the same.
9 u - 20 = 4 u + 80
9 u - 4 u = 80 + 20
5 u = 100
1 u = 100 ÷ 5 = 20
Number of stamps that Wesley has now
= 9 u - 20 + 4 u + 80
= 9 u + 4 u - 20 + 80
= 13 u + 60
= 13 x 20 + 60
= 260 + 60
= 320
Answer(s): 320