Question

Giuliana has 22 quarters and dollar coins worth a total of $10.75.

Which equation can be used to find d, the number of dollar coins Giuliana has?

Answer 1

The answer is d + 0.25(d - 22) = 10.75

d - the amount of dollar coins
q - the amount of quarters

It is given: d + q = 22

The quarter is $0.25, therefore:
d + 0.25q = 10.75

Now, we have the system of equations:
d + q = 22
d + 0.25q = 10.75

According to the first equation:
d + q = 22 ⇒ q = 22 - d

We will replace q in the second equation:
d + 0.25q = 10.75 ⇒ d + 0.25(22 - d) = 10.75