Frequency response of digital filter

I have a transfer function given as U(z) =5H(z)z^-1/(1-4z^-5+6H(z)z^-7) ,

where H(z) is H(z)=B(z)/A(z) is discrete-time filter specified by the input vectors, b and a. The input vectors are the coefficients for the numerator, b, and denominator, a, polynomials in z^-1.

How to plot in frequency domain?considering sampling time 'fs' and frequency span 'f'.