David and Abi had the same number of mochi balls. After Abi gave away 21 mochi balls and David gave away 36 mochi balls, Abi had 4 times as many mochi balls as David. How many mochi balls did each of them have at first?
| |
David |
Abi |
| Before |
1 u + 36 |
4 u + 21 |
| Change |
- 36 |
- 21 |
| After |
1 u |
4 u |
The number of mochi balls that David and Abi had at first is the same.
4 u + 21 = 1 u + 36
4 u - 1 u = 36 - 21
3 u = 15
1 u = 15 ÷ 3 = 5
Number of mochi balls that each of them had at first
= 1 u + 36
= 5 + 36
= 41
Answer(s): 41
