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.