2t-10/t^2 -25 the denominator is the difference of two squares
(2t - 10) / {(t+5)(t-5)} take out common factor of 2 from numerator
2(t-5) / {(t+5)(t-5)} cancel common term, (t-5), top and bottom
2/(t+5)
In lowest terms, the expression becomes: 2/(t+5)