Teacher Liu has to give art classes to 3 classes every day, and the number of students in each class is between 42-47. How many students does Teacher Liu teach every day?
刘老师每天要给3个班上美术课，每个班学生人数都在42-47人之间，刘老师每天大约要给多少个学生上课．
<gadget id="calculator">120 - 150</gadget>
<output>-30</output>

<result>-30</result>