The expression is  .

      (Substitute 12,and 7 for b and c) \ \ To simplify the expression follow the order of operations: (PEMDAS)

1.     Evaluate the expressions inside Brackets/Parenthesis (P).

2.     Evaluate Powers/Exponents (E).

3.     Multiply and/or Divide in order from left to right (MD).

4.     Add and/or Subtract in order from left to right (AS).

A simple technique for remembering the order pf operations is turned into phrase

“Please Excuse My Dear Aunty Sally”

According order of operations inside the grouping symbols should be

evaluated first.

First operation is subtracting the numbers within the parenthesis.

                     (Multiply:

Next operation is subtracted.

                               (Subtract: )

Next operation is multiplication.

                                  (Multiply: )

Next operation is subtraction.

                                            (Subtract: )

The value of the expression is 1.