David and Ahmad had 72 pens. After David gave 23 pens to Ahmad. Ahmad, in return, gave half of his pens to David. In the end, David had twice as many pens as Ahmad. How many pens did David have at first?
| |
David |
Ahmad |
Total |
| Before |
1 u + 23 |
2 u - 23 |
72 |
| Change 1 |
- 23 |
+ 23 |
|
| After 1 |
1 u |
2 u |
|
| Change 2 |
+ 1 u |
- 1 u |
|
| After 2 |
2 u |
1 u |
72 |
Total number of pens that David and Ahmad had at first and in the end remains unchanged.
Total number of pens
= 2 u + 1 u
= 3 u
1 u = 72 ÷ 3 = 24
Number of pens that David had at first
= 1 u + 23
= 24 + 23
= 47
Answer(s): 47
