Multiply both sides of the equation by .

Multiply by .

Subtract from both sides of the equation.

Factor out of .

Factor out of .

Factor out of .

Rewrite as .

Divide each term in by .

Cancel the common factor of .

Cancel the common factor.

Divide by .

Simplify .

Move the negative in front of the fraction.

Combine the numerators over the common denominator.

Factor out of .

Factor out of .

Factor out of .

Factor out of .

Solve for f (af)/b=f+c-d