Oscar had some erasers at first. After he bought another 72 erasers, he had thrice as many erasers as before. How many erasers did Oscar have at first?
|
Erasers |
Before |
1 u |
Change |
+ 72 |
After |
1 u + 72 = 3 u |
Number of erasers after he bought = 1 u + 72
Number of erasers that is thrice as many erasers as before = 3 x 1 u = 3 u
3 u = 1 u + 72
3 u - 1 u = 72
2 u = 72
1 u = 72 ÷ 2 = 36
Number of stickers that Kim had at first
= 1 u
= 36
Answer(s): 36