If a/b = 1/3, then (3a + 2b) / (3a - 2b) is equal to?

Given expression = (3a + 2b) / (3a - 2b)
= [3(a/b) + 2] / [3(a/b) - 2]
= [3 x 1/3 + 2] / [3 x 1/3 - 2]
= 3 / -1
=-3