Zoe and Christian had an equal number of mochi balls at first. After Zoe bought another 9 mochi balls and Christian lost 9 mochi balls, Zoe had thrice as many mochi balls as Christian. Find the number of mochi balls each of them had at first.
| |
Zoe |
Christian |
| Before |
3 u - 9 |
1 u + 9 |
| Change |
+ 9 |
- 9 |
| After |
3 u |
1 u |
The number of mochi balls that Zoe and Christian at first is the same.
3 u - 9 = 1 u + 9
3 u - 1 u = 9 + 9
2 u = 18
1 u = 18 ÷ 2 = 9
Number of mochi balls that each of them had at first
= 1 u + 9
= 9 + 9
= 18
Answer(s): 18
