Mr. Johnson has two part-time jobs. On weekdays, he works 4 hours each day at a bookstore and 3 hours each day at a coffee shop. On weekends, he works 5 hours each day at the bookstore and 2 hours each day at the coffee shop. If he earns $15 per hour at the bookstore and $12 per hour at the coffee shop, calculate his total earnings for a week. Let's think step by step and output the final answer within \boxed{}.
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