The steps in achieving the answer for the simplification are as follows:
1. The least common multiple of the denominators of the terms of the given is ab.
2. Multiply the expression with ab, such that,
(xy/a - 1/b) x (ab)
3. Simplifying,
xyb - a
4. Writing ab as the denominator of the expression in number, we get the final answer which is equal to,
(xyb - a)/ab