The equation is f – (– 40) = – 12.

f + 40 = –12                 (Product of two same signs is positive)

Apply subtraction property of equality: Subtract 40 from each side.

f + 40 – 40 = –12–40

         (Apply additive inverse property: )

               (Apply additive identity property: )

                       (Add: )

Check:

To check the solution, substitute f = –52 in original equation.

f + 40 = –12 –52 + 40 = –12

– 12 = – 12                  (Add: –52 + 40 = –12)

The statement is true.

The value of f = –52.