You want to isolate C, so the first step would to have it be positive. You would do this by adding C to both sides of the equation to cancel the C on one of the sides out like this: [tex]p + c = r - c + c \\ p + c = r[/tex] . Then you want to cancel out the P, so you subtract it on both sides like this: [tex]c + p - p = r - p \\ c = r - p[/tex] And that is your answer
