The ratio of the number of blue pens to green pens is 9 : 4. After Albert gives away 10 blue pens and buys another 70 green pens, there is equal number of blue pens and green pens. How many pens does Albert have now?
| |
Blue |
Green |
| Before |
9 u |
4 u |
| Change |
- 10 |
+ 70 |
| After |
9 u - 10 |
4 u + 70 |
The number of blue pens and green pens in the end is the same.
9 u - 10 = 4 u + 70
9 u - 4 u = 70 + 10
5 u = 80
1 u = 80 ÷ 5 = 16
Number of pens that Albert has now
= 9 u - 10 + 4 u + 70
= 9 u + 4 u - 10 + 70
= 13 u + 60
= 13 x 16 + 60
= 208 + 60
= 268
Answer(s): 268
