#### Answer

1/3; m cannot equal 2.5

#### Work Step by Step

In order to simplify, we want something to be both in the numerator and the denominator of the fraction so it can be canceled out. Thus, we factor and obtain:
$(2m-5) / (6m-15) \\\\ (2m-5)/3(2m-5) \\\\ 1/3$
m cannot equal 2.5, for if m equaled 2.5, the denominator of the fraction would cancel out to 0, which is not allowed.