Oliver had 6 times as many pens as Warren at first. Then each of them bought an equal number of new pens. In the end, Warren had 35 pens and Oliver had 4 times as many pens as Warren. How many pens did both of them buy altogether?
| |
Oliver |
Warren |
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 Warren had in the end = 5 u
5 u = 35
1 u = 35 ÷ 5 = 7
Number of pens that Oliver bought
= 20 u - 18 u
= 2 u
Number of pens that both of them bought altogether
= 2 x 2 u
= 4 u
= 4 x 7
= 28
Answer(s): 28
