Teacher: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.
Teacher: Now, understand the problem? Solve this instance: before lunch a waitress had already earned $ 5 in tips . after lunch she had 7 customers and each customer gave her a 2 dollar tip . how much money did she earn total ?
Student:
19