I'm completely lost with this math problem: Hallie is working as a waitress for $10/hour. On Monday, she works for 7 hours, and she receives $18 in tips. On Tuesday she works for 5 hours, and she receives $12 in tips. On Wednesday she works for 7 hours, and she receives $20 in tips. How much money does she earn in total from Monday to Wednesday?
Can you give me a hand?