A local train service runs a shuttle between two towns. On a certain day, the train carried 75 passengers from Town A to Town B in the morning and 45 passengers from Town B to Town A in the afternoon. If the train made two additional round trips that day, carrying the same number of passengers as the first trip in each trip, calculate the total number of passengers transported between both towns. Let's think step by step and output the final answer within \boxed{}.
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