Diana bought some pens. She gave
15 of the pens to her cousin and sold
35 of the remaining pens. After that, she bought another 102 pens and had the same number of pens that she bought at first. How many pens did Diana buy at first?
| Her cousin |
Remaining pens |
Bought pens |
Total |
1x5 =
5 u |
4x5 =
20 u |
|
5x5 =
25 u |
| |
Sold |
Left |
|
|
| |
3x4 |
2x4 |
|
|
| 5 u |
12 u |
8 u |
102 |
|
The remaining number of pens before Diana bought another 102 pens is repeated. Make the remaining number of pens the same. LCM of 4 and 5 is 20.
Total number of pens at first = 25 u
Number of pens that Diana had left and bought after that = 8 u + 102
25 u = 8 u + 102
25 u - 8 u = 102
17 u = 102
1 u = 102 ÷ 17 = 6
Total number of pens at first
= 25 u
= 25 x 6
= 150
Answer(s): 150
