A sum of money amounting to $4.15 consists of dimes and quarters. If there are 28

coins in all, how many are quarters?

there are 9 quarters and 19 dimes

Step-by-step explanation:

Let x be the number of dimes and y the number of quarters

-dimes: 0.1x

-quarters: 0.25y

-the total amount of coins : x + y = 28

=> x = 28 - y

We have the equation:

0.25y + 0.1x = 4.15

0.25y + 0.1 (28 - y) = 4.15

0.25y + 2.8 - 0.1y = 4.15

0.15y = 1.35

y = 9

x = 28 - y

= 28 - 9

= 19