Jack has 70% as many coins as Vincent. If Jack gives away 50% of the coins and Vincent gives away 40% of his coins, they will have 38 coins altogether. How many coins do the two of them have?
| |
Jack |
Vincent |
Total |
Comparing Jack
and Vincent at first |
7x2 =
14 u |
10x2 =
20 u |
|
| Before |
2x7 =
14 u |
5x4 =
20 u |
|
| Change |
- 1x7 =
- 7 u |
- 2x4 =
- 8 u |
|
| After |
1x7 =
7 u |
3x4 =
12 u |
38 |
70% =
70100 =
710 50% =
50100 =
12 40% =
40100 =
25 The number of coins that Jack has at first is repeated. Make the number of coins that Jack has the same. LCM of 7 and 2 is 14 u.
The number of coins that Vincent has at first is repeated. Make the number of coins that Vincent has the same. LCM of 10 and 5 is 20 u.
Number of coins in the end
= 7 u + 12 u
= 19 u
19 u = 38
1 u = 38 ÷ 19 = 2
Total number of coins that the two of them have
= 14 u + 20 u
= 34 u
= 34 x 2
= 68
Answer(s): 68
