To subtract fractions, let's put a generic example. Be the fractions (a / b) - (c / d) With a, b, c and d other than zero. The subtraction of fractions is given by: (a / b) - (c / d) = ((a * d) - (c * b)) / (b * d). If the fractions have the same denominator then the subtraction is (a / b) - (c / b) = (a-c) / (b) answer (a / b) - (c / d) = ((a * d) - (c * b)) / (b * d) (a / b) - (c / b) = (a-c) / (b)