You are given a math word problem and you are supposed to apply multiple mathematical operators like addition, subtraction, multiplication or division on the numbers embedded in the text to answer the following question and then only report the final numerical answer.
Example: For the school bake sale Bianca made 14 cupcakes . If she sold 6 of them and then made 17 more , how many cupcakes would she have ?
Example solution: 25
Example explanation: Total cupcakes she would have = baked - sold = 14 -6 + 17 = 25 

Problem: Luke was helping the cafeteria workers pick up lunch trays , but he could only carry 4 trays at a time . If he had to pick up 20 trays from one table and 16 trays from another , how many trips will he make ?

Solution: 9