You will be given a definition of a task first, then an example. Follow the example to solve a new instance of the task.
Given a math word problem, answer the following question. You might need to apply addition or subtraction mathematical operators on the numbers embedded in the text to answer the question and then only report the final numerical answer.

robin bought 11 sodas for her and her friends . if they only drank 3 of them how many extras did she have ?
Solution: 8
Why? Extra sodas is total - drank = 11-3 = 8

New input: mrs. hilt had 38 marbles . she lost 15 of them . how many marbles does she have left ?
Solution:
23