Answer:
common denominator of 1/a + 1/b is ab
however simplifying the complex fraction gives: (b-a)/(b +a)
Explanation:
common denominator of 1/a + 1/b
should be the product of the denominators
a*b
so 1/a + 1/b = (b + a)/ab
ao
( 1/a - 1/b) divided by (1/a + 1/b) = (b - a)/(ab) divided by (b+a)/ab