Last week, Jack had a total of 255 yellow and silver pens. Two weeks later, he sold
34 of all the yellow pens and bought another 20 silver pens. Now he has the same number of yellow and silver pens. How many pens does he have in the end?
| |
Yellow |
Silver |
Total |
| Before |
4 u |
1 u - 20 |
5 u - 20 |
| Change |
- 3 u |
+ 20 |
|
| After |
1 u |
1 u |
|
Comparing the yellow
and silver pens in the end |
1 |
1 |
|
Total number of pens at first
= 4 u + 1 u - 20
= 5 u - 20
5 u - 20 = 255
5 u = 255 + 20
5 u = 275
1 u = 275 ÷ 5 = 55
Number of pens that he has in the end
= 1 u + 1 u
= 2 u
= 2 x 55
= 110
Answer(s): 110
