The ratio of the number of green erasers to blue erasers is 9 : 4. After Xavier gives away 50 green erasers and buys another 70 blue erasers, there is equal number of green erasers and blue erasers. How many erasers does Xavier have now?
| |
Green |
Blue |
| Before |
9 u |
4 u |
| Change |
- 50 |
+ 70 |
| After |
9 u - 50 |
4 u + 70 |
The number of green erasers and blue erasers in the end is the same.
9 u - 50 = 4 u + 70
9 u - 4 u = 70 + 50
5 u = 120
1 u = 120 ÷ 5 = 24
Number of erasers that Xavier has now
= 9 u - 50 + 4 u + 70
= 9 u + 4 u - 50 + 70
= 13 u + 20
= 13 x 24 + 20
= 312 + 20
= 332
Answer(s): 332
