Cody has a total of 14 fifty-cent and twenty-cent coins. The total value of the coins is $4. If he spends all the fifty-cent coins on a pen, how much does the pen cost?
Number of
fifty-cent coins |
Value of
fifty-cent coins |
Number of
twenty-cent coins |
Value of
twenty-cent coins |
Total
value |
| 14 |
14 x 50
= 700¢ |
0 |
0 |
700¢ |
| 13 |
13 x 50
= 650¢ |
1 |
1 x 20
= 20¢ |
670¢ |
| 4 |
4 x 50
= 200¢ |
10 |
10 x 20
= 200¢ |
400¢ |
$1 = 100¢
$4 = 400¢
Total value if all the coins are fifty-cent coins
= 14 x 50
= 700¢
Big difference between the value of fifty-cent coins and twenty-cent coins
= 700 - 400
= 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
= 14 - 10
= 4
Cost of the pen
= 4 x 50
= 200¢
= $2
Answer(s): $2
