The ratio of the number of red stamps to blue stamps is 3 : 1. After Albert gives away 30 red stamps and buys another 50 blue stamps, there is equal number of red stamps and blue stamps. How many stamps does Albert have now?
| |
Red |
Blue |
| Before |
3 u |
1 u |
| Change |
- 30 |
+ 50 |
| After |
3 u - 30 |
1 u + 50 |
The number of red stamps and blue stamps in the end is the same.
3 u - 30 = 1 u + 50
3 u - 1 u = 50 + 30
2 u = 80
1 u = 80 ÷ 2 = 40
Number of stamps that Albert has now
= 3 u - 30 + 1 u + 50
= 3 u + 1 u - 30 + 50
= 4 u + 20
= 4 x 40 + 20
= 160 + 20
= 180
Answer(s): 180
