Answer:
r = (C - By) / A
Explanation:
Ar + By = C
_________
-By -By
[Subtract both sides by By (Subtraction poe)]
Ar = C - By
________
(Ar) = (C - By)
[Use parenthesis to group both terms (Associative property of equality)]
________
÷A ÷A
[Divide both sides by A to isolate r so it can be solved (Division poe)]
________
r = (C - By) / A