Stuck in the homework

Question

To solve the HW2 recovery program, I defined a function that describes one simple transaction, that should correspond to the ex1(transact_log) parameter. So, given a sender, a receiver, the amount transferred, the intermediary account and the commission, I can see how much money after the single transaction each account has. But I don't know how to move forward, and neither if this is the best course of action. Any help or suggestion would be highly appreciated! Thanks in advance for the attention and take care