Question

Tom has $5.05 in quarters and dimes. How many coins are dimes if the total number of coins is 28?  Try creating a system of equations and solving this by either substitution or elimination.[d] dimes

Answer 1

In this case, we'll have to carry out several steps to find the solution.

Step 01:

total money = $5.05

total coins = 28

x = ?

y = ?

Step 02:

system of equations

x = quarters

y = dimes

x + y = 28 eq.1

0.25x + 0.10y = 5.05 eq.2

x + y = 28 *(-0.25)

0.25x + 0.10y = 5.05

-0.25x -0.25y = -7

0.25x + 0.10y = 5.05

------------------------------------

-0.15y = -1.95

y = -1.95 / -0.15 = 13

y in eq.1

x + 13 = 28

x = 28 - 13 = 15

The answer is:

There are 15 quarters and 13 dimes.