The ratio of the number of red erasers to blue erasers is 9 : 4. After Reggie gives away 50 red erasers and buys another 90 blue erasers, there is equal number of red erasers and blue erasers. How many erasers does Reggie have now?
| |
Red |
Blue |
| Before |
9 u |
4 u |
| Change |
- 50 |
+ 90 |
| After |
9 u - 50 |
4 u + 90 |
The number of red erasers and blue erasers in the end is the same.
9 u - 50 = 4 u + 90
9 u - 4 u = 90 + 50
5 u = 140
1 u = 140 ÷ 5 = 28
Number of erasers that Reggie has now
= 9 u - 50 + 4 u + 90
= 9 u + 4 u - 50 + 90
= 13 u + 40
= 13 x 28 + 40
= 364 + 40
= 404
Answer(s): 404
