Help with H(z) response function

Hello, i have simple task. Calculate the transfer function H(z). Figure shows block diagram of the filters structure. I think transfer function is :

a_parallel = parallel(Hz1,Hz2);
b_serial = series(a_parallel,Hz3);

But i dont know how to write H1(z), H2(z), H3(z). Anyone can help me to write H1(z), H2(z), H3(z)?

Answer 1

[Azzi Abdelmalek]

ts=1  % Sample time
H1=tf([2/3 2/5 4/7],[1 0 0],ts)
H2=tf([4/3 8/5 3/7],[1 0 0],ts)
H3=tf([3 2 4],[1 0 0],ts)
H=(H1+H2)*H3

%or

H=series(parallel(H1,H2),H3)

[John Cober]

Thank you. But why H is not equal to the answer in picture? And task H1, H2, H3 not equal to Matlab output window. Matlab H1 = Transfer function: (0.6667 z^2 + 0.4 z + 0.5714)/z^2 Task H1 = 2/3 + (2/5)*z^-1 + (4/7)*z^-2

[Azzi Abdelmalek]

The result is the same

Answer 2

[Honglei Chen]

conv(([2/3 2/5 4/7]+[4/3 8/5 3/7]),[3 2 4])