You are given a math word problem and you are supposed to apply addition or subtraction mathematical operators on the numbers embedded in the text to answer the following question and then only report the final numerical answer.

[EX Q]: For a birthday party Jerry bought 41 regular sodas and 22 diet sodas . If his fridge would only hold 9 on each shelf , how many shelves would he fill up ?
[EX A]: 7

[EX Q]: For his car , Mike spent $ 118.54 on speakers and $ 106.33 on new tires . Mike wanted 3 CD 's for $ 4.58 but decided not to . In total , how much did Mike spend on car parts ?
[EX A]: 224.87

[EX Q]: A waiter at ' The Greasy Spoon ' restaurant had 29 customers to wait on . During the lunch rush he added another 20 customers . If 34 of the customers did n't leave him a tip , how many customers did leave a tip ?
[EX A]:
15