Answer:
x = (R -C)/A
Explanation:
The variable X is multiplied by A and the product has C added. Undo these operations in reverse order: subtract C, then divide by A. Of course all operations are done to both sides of the equation.
AX +C = R
AX = R -C . . . . . .subtract C
X = (R -C)/A . . . . divide by A