The ratio of the number of blue pens to green pens is 3 : 1. After Brandon gives away 10 blue pens and buys another 40 green pens, there is equal number of blue pens and green pens. How many pens does Brandon have now?
| |
Blue |
Green |
| Before |
3 u |
1 u |
| Change |
- 10 |
+ 40 |
| After |
3 u - 10 |
1 u + 40 |
The number of blue pens and green pens in the end is the same.
3 u - 10 = 1 u + 40
3 u - 1 u = 40 + 10
2 u = 50
1 u = 50 ÷ 2 = 25
Number of pens that Brandon has now
= 3 u - 10 + 1 u + 40
= 3 u + 1 u - 10 + 40
= 4 u + 30
= 4 x 25 + 30
= 100 + 30
= 130
Answer(s): 130
