John had some erasers at first. After he bought another 78 erasers, he had seven times as many erasers as before. How many erasers did John have at first?
| |
Erasers |
| Before |
1 u |
| Change |
+ 78 |
| After |
1 u + 78 = 7 u |
Number of erasers after he bought = 1 u + 78
Number of erasers that is seven times as many erasers as before = 7 x 1 u = 7 u
7 u = 1 u + 78
7 u - 1 u = 78
6 u = 78
1 u = 78 ÷ 6 = 13
Number of stickers that Kim had at first
= 1 u
= 13
Answer(s): 13
