Will has a total of 16 fifty-cent and twenty-cent coins. The total value of the coins is $5. If he spends all the fifty-cent coins on a file, how much does the file cost?
Number of
fifty-cent coins |
Value of
fifty-cent coins |
Number of
twenty-cent coins |
Value of
twenty-cent coins |
Total
value |
| 16 |
16 x 50
= 800¢ |
0 |
0 |
800¢ |
| 15 |
15 x 50
= 750¢ |
1 |
1 x 20
= 20¢ |
770¢ |
| 6 |
6 x 50
= 300¢ |
10 |
10 x 20
= 200¢ |
500¢ |
$1 = 100¢
$5 = 500¢
Total value if all the coins are fifty-cent coins
= 16 x 50
= 800¢
Big difference between the value of fifty-cent coins and twenty-cent coins
= 800 - 500
= 300¢
Small difference between the value of one fifty-cent coin and one twenty-cent coin
= 50 - 20
= 30¢
Number of twenty-cent coins
= 300 ÷ 30
= 10
Number of fifty-cent coins
= 16 - 10
= 6
Cost of the file
= 6 x 50
= 300¢
= $3
Answer(s): $3
