How to solve it simply to get difference equation have three branches meet to give y(n), 2 are coming from delayed output one coming from input

Question

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In Figure.3 a block diagram of a certain system is shown with input 𝑥(𝑛) and output 𝑦(𝑛). a. Find the difference equation that relates input to output. b. Find the system transfer function 𝐻(𝑧).