You have the following function;
the vertical asymptote is obtained by making the denominator equal to zero and solving for x:
x + 4 = 0
x = -4
The vertical asymptote is x = -4
The horizontal asymptote, for the cases in which the degree of the numerator is equal to the degree of the denominator, is equal to the quotient between the leadding coefficients:
y = 3/1 = 3
The horizontal asymptote is y = 3