Simplify the following expression completely.

(x^2 - 18x + 80)/(x^2 -16x + 60)

To simplify the expression, we can factor the numerator and denominator.

The numerator can be factored as:
(x^2 - 18x + 80) = (x - 10)(x - 8)

The denominator can be factored as:
(x^2 - 16x + 60) = (x -10)(x - 6)

Now, we can cancel out the common factors:
[(x - 10)(x - 8)] / [(x -10)(x - 6)]
= (x - 8) / (x - 6)

Therefore, the simplified expression is (x - 8) / (x - 6).