Step 1 :Compare the degrees of the numerator and denominator. In this case, both degrees are equal (both are 1).
Step 2 :Find the ratio of the leading coefficients, which are -3 and 5.
Step 3 :\(\frac{-3}{5} = -0.6\)
Step 4 :\(\boxed{y = -\frac{3}{5}}\) or \(\boxed{y = -0.6}\) is the horizontal asymptote of the given rational function.