The ratio of the number of red erasers to blue erasers is 8 : 5. After Vaidev gives away 20 red erasers and buys another 70 blue erasers, there is equal number of red erasers and blue erasers. How many erasers does Vaidev have now?
| |
Red |
Blue |
| Before |
8 u |
5 u |
| Change |
- 20 |
+ 70 |
| After |
8 u - 20 |
5 u + 70 |
The number of red erasers and blue erasers in the end is the same.
8 u - 20 = 5 u + 70
8 u - 5 u = 70 + 20
3 u = 90
1 u = 90 ÷ 3 = 30
Number of erasers that Vaidev has now
= 8 u - 20 + 5 u + 70
= 8 u + 5 u - 20 + 70
= 13 u + 50
= 13 x 30 + 50
= 390 + 50
= 440
Answer(s): 440
