Dylan had 6 times as many pens as Oscar at first. Then each of them bought an equal number of new pens. In the end, Oscar had 40 pens and Dylan had 4 times as many pens as Oscar. How many pens did both of them buy altogether?
| |
Dylan |
Oscar |
Difference |
| Before |
6x3 =
18 u |
1x3 =
3 u |
5x3 =
15 u |
| Change |
+ ? |
+ ? |
|
| After |
4x5 =
20 u |
1x5 =
5 u |
3x5 =
15 u |
The difference in the number of pens at first and in the end remains unchanged. Make the difference in the number of pens at first and in the end the same. LCM of 5 and 3 is 15.
Number of pens that Oscar had in the end = 5 u
5 u = 40
1 u = 40 ÷ 5 = 8
Number of pens that Dylan bought
= 20 u - 18 u
= 2 u
Number of pens that both of them bought altogether
= 2 x 2 u
= 4 u
= 4 x 8
= 32
Answer(s): 32
