Hilda bought some erasers. She gave
15 of the erasers to her sister and sold
56 of the remaining erasers. After that, she bought another 91 erasers and had the same number of erasers that she bought at first. How many erasers did Hilda buy at first?
| Her sister |
Remaining erasers |
Bought erasers |
Total |
1x3 =
3 u |
4x3 =
12 u |
|
5x3 =
15 u |
| |
Sold |
Left |
|
|
| |
5x2 |
1x2 |
|
|
| 3 u |
10 u |
2 u |
91 |
|
The remaining number of erasers before Hilda bought another 91 erasers is repeated. Make the remaining number of erasers the same. LCM of 4 and 6 is 12.
Total number of erasers at first = 15 u
Number of erasers that Hilda had left and bought after that = 2 u + 91
15 u = 2 u + 91
15 u - 2 u = 91
13 u = 91
1 u = 91 ÷ 13 = 7
Total number of erasers at first
= 15 u
= 15 x 7
= 105
Answer(s): 105
