Ivan had
310 as many coins as Zoe. After Ivan bought another 3 coins, he had 18 less coins than Zoe. How many coins did Ivan have at first?
|
Ivan |
Zoe |
Before |
3 u |
10 u |
Change |
+ 3 |
|
After |
3 u + 3 |
10 u |
Zoe had 18 more coins than Ivan in the end. So, if Ivan had another 18 coins, he would have the same number of coins as Zoe.
10 u = 3 u + 3 + 18
10 u - 3 u = 3 + 18
7 u = 21
1 u = 21 ÷ 7 = 3
Number of coins that Ivan had at first
= 3 u
= 3 x 3
= 9
Answer: 9