The ratio of the number of green erasers to red erasers is 9 : 4. After Elijah gives away 20 green erasers and buys another 50 red erasers, there is equal number of green erasers and red erasers. How many erasers does Elijah have now?
| |
Green |
Red |
| Before |
9 u |
4 u |
| Change |
- 20 |
+ 50 |
| After |
9 u - 20 |
4 u + 50 |
The number of green erasers and red erasers in the end is the same.
9 u - 20 = 4 u + 50
9 u - 4 u = 50 + 20
5 u = 70
1 u = 70 ÷ 5 = 14
Number of erasers that Elijah has now
= 9 u - 20 + 4 u + 50
= 9 u + 4 u - 20 + 50
= 13 u + 30
= 13 x 14 + 30
= 182 + 30
= 212
Answer(s): 212
