Justin had 5 times as many pens as Henry at first. Then each of them bought an equal number of new pens. In the end, Henry had 4 pens and Justin had 3 times as many pens as Henry. How many pens did both of them buy altogether?
| |
Justin |
Henry |
Difference |
| Before |
5x1 =
5 u |
1x1 =
1 u |
4x1 =
4 u |
| Change |
+ ? |
+ ? |
|
| After |
3x2 =
6 u |
1x2 =
2 u |
2x2 =
4 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 4 and 2 is 4.
Number of pens that Henry had in the end = 2 u
2 u = 4
1 u = 4 ÷ 2 = 2
Number of pens that Justin bought
= 6 u - 5 u
= 1 u
Number of pens that both of them bought altogether
= 2 x 1 u
= 2 u
= 2 x 2
= 4
Answer(s): 4
