Sasha can complete 15 questions an hour. If she has 60 questions to complete and she works for 2 hours, how many questions does she still need to complete?
Sasha completes 15 questions/hour * 2 hours = 
<gadget id="calculator">15*2</gadget>
<output>30</output>
30 questions.
This means there are still 60 questions - 30 questions = 
<gadget id="calculator">60-30</gadget>
<output>30</output>
30 questions left to complete.

<result>30</result>