David had
25 as many marbles as Xuan. After David gave away 72 marbles, he had 93 less marbles than Xuan. How many marbles did Xuan have?
| |
David |
Xuan |
| Before |
2 u |
5 u |
| Change |
- 72 |
|
| After |
2 u - 72 |
5 u |
Xuan had 93 more marbles than David in the end. So, if David had another 93 marbles, he would have the same number of marbles as Xuan.
5 u = 2 u - 72 + 93
5 u - 2 u = 93 - 72
3 u = 21
1 u = 21 ÷ 3 = 7
Number of marbles that Xuan had at first
= 5 u
= 5 x 7
= 35
Answer: 35
