The ratio of the number of blue erasers to green erasers is 7 : 2. After Carl gives away 30 blue erasers and buys another 80 green erasers, there is equal number of blue erasers and green erasers. How many erasers does Carl have now?
| |
Blue |
Green |
| Before |
7 u |
2 u |
| Change |
- 30 |
+ 80 |
| After |
7 u - 30 |
2 u + 80 |
The number of blue erasers and green erasers in the end is the same.
7 u - 30 = 2 u + 80
7 u - 2 u = 80 + 30
5 u = 110
1 u = 110 ÷ 5 = 22
Number of erasers that Carl has now
= 7 u - 30 + 2 u + 80
= 7 u + 2 u - 30 + 80
= 9 u + 50
= 9 x 22 + 50
= 198 + 50
= 248
Answer(s): 248
