When the denominators are the same, you add the numerators and place the sum over the common denominator. When the denominators are the same, you subtract the numerators and place the difference over ...When the denominators are the same, you add the numerators and place the sum over the common denominator. When the denominators are the same, you subtract the numerators and place the difference over the common denominator. The fractions have a common denominator, so add the numerators and place the sum over the common denominator. To add rational expressions with a common denominator, add the numerators and place the sum over the common denominator.
