Ian, David and Ahmad shared a bag of stamps. David took 25 as many stamps as Ahmad. Ian took twice as many stamps as the total David and Ahmad took. After Ian had given 30 to David and 5 to Ahmad, David gave 5 to Ahmad. In the end, all three of them had the same number of stamps. Find the difference between the number of stamps that Ian and David had at first.
| |
David |
Ahmad |
Ian |
Total |
| Before |
2 u |
5 u |
14 u |
21 u |
| Change 1 |
+ 30 |
|
- 30 |
|
| Change 2 |
|
+ 5 |
- 5 |
|
| Change 3 |
- 5 |
+ 5 |
|
|
| After |
1x7 =
7 u |
1x7 =
7 u |
1x7 =
7 u |
3x7 =
21 u |
Total number of stamps that David and Ahmad had at first
= 2 u + 5 u
= 7 u
Number of stamps that Ian had at first
= 2 x 7 u
= 14 u
The total number of stamps remains unchanged. Make the total number of stamps the same. LCM of 3 and 21 is 21.
Number of stamps that Ahmad received from David and Ian
= 7 u - 5 u
= 2 u
2 u = 5 + 5
2 u = 10
1 u = 10 ÷ 2 = 5
Difference between the number stamps that Ian and David had at first
= 14 u - 2 u
= 12 u
= 12 x 5
= 60
Answer(s): 60
