A furniture factory needs to make 250 sets of furniture. It has been done for 15 days, with an average of 13 sets per day. How many sets are left?
一个家具厂要做250套家具，已经做了15天，平均每天做了13套，还剩多少套没有做？
<gadget id="calculator">15 * 13</gadget>
<output>195</output>

<gadget id="calculator">250 - 195</gadget>
<output>55</output>

<result>55</result>