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

Given:
22 quarters and dollar coins worth 10.75

quarters = 0.25 
dollar = 1.00

q + d = 22
0.25q + d = 10.75

q = 22 - d
0.25(22-d) + d = 10.75 

5.5 - 0.25d + d = 10.75
0.75d = 10.75 - 5.5
0.75d = 5.25
d = 5.25/0.75
d = 7