Mark and Wesley had 51 pens. After Mark gave 10 pens to Wesley. Wesley, in return, gave half of his pens to Mark. In the end, Mark had twice as many pens as Wesley. How many pens did Mark have at first?
| |
Mark |
Wesley |
Total |
| Before |
1 u + 10 |
2 u - 10 |
51 |
| Change 1 |
- 10 |
+ 10 |
|
| After 1 |
1 u |
2 u |
|
| Change 2 |
+ 1 u |
- 1 u |
|
| After 2 |
2 u |
1 u |
51 |
Total number of pens that Mark and Wesley had at first and in the end remains unchanged.
Total number of pens
= 2 u + 1 u
= 3 u
1 u = 51 ÷ 3 = 17
Number of pens that Mark had at first
= 1 u + 10
= 17 + 10
= 27
Answer(s): 27
