Ahmad has a total of 20 fifty-cent and ten-cent coins. The total value of the coins is $6. If he spends all the fifty-cent coins on a marker, how much does the marker cost?
Number of
fifty-cent coins |
Value of
fifty-cent coins |
Number of
ten-cent coins |
Value of
ten-cent coins |
Total
value |
| 20 |
20 x 50
= 1000¢ |
0 |
0 |
1000¢ |
| 19 |
19 x 50
= 950¢ |
1 |
1 x 10
= 10¢ |
960¢ |
| 10 |
10 x 50
= 500¢ |
10 |
10 x 10
= 100¢ |
600¢ |
$1 = 100¢
$6 = 600¢
Total value if all the coins are fifty-cent coins
= 20 x 50
= 1000¢
Big difference between the value of fifty-cent coins and ten-cent coins
= 1000 - 600
= 400¢
Small difference between the value of one fifty-cent coin and one ten-cent coin
= 50 - 10
= 40¢
Number of ten-cent coins
= 400 ÷ 40
= 10
Number of fifty-cent coins
= 20 - 10
= 10
Cost of the marker
= 10 x 50
= 500¢
= $5
Answer(s): $5
