Ryan has a total of 13 fifty-cent and twenty-cent coins. The total value of the coins is $5. If he spends all the fifty-cent coins on a notebook, how much does the notebook cost?
Number of fifty-cent coins |
Value of fifty-cent coins |
Number of twenty-cent coins |
Value of twenty-cent coins |
Total value |
13 |
13 x 50 = 650¢ |
0 |
0 |
650¢ |
12 |
12 x 50 = 600¢ |
1 |
1 x 20 = 20¢ |
620¢ |
8 |
8 x 50 = 400¢ |
5 |
5 x 20 = 100¢ |
500¢ |
$1 = 100¢
$5 = 500¢
Total value if all the coins are fifty-cent coins
= 13 x 50
= 650¢
Big difference between the value of fifty-cent coins and twenty-cent coins
= 650 - 500
= 150¢
Small difference between the value of one fifty-cent coin and one twenty-cent coin
= 50 - 20
= 30¢
Number of twenty-cent coins
= 150 ÷ 30
= 5
Number of fifty-cent coins
= 13 - 5
= 8
Cost of the notebook
= 8 x 50
= 400¢
= $4
Answer(s): $4