Six days before the start of school, Xiao Ming has not done his winter vacation math homework, but Xiao Qiang has completed 60 questions. At the beginning of school, both of them completed their math homework. During these 6 days, Xiao Ming did three times as many questions as Xiao Qiang. How many questions did he do on average every day?
开学前6天，小明还没做寒假数学作业，而小强已完成了60道题．开学时，两人都完成了数学作业，在这6天中，小明做的题的数目是小强的3倍，他平均每天做了多少道题．
<gadget id="calculator">3 - 1</gadget>
<output>2</output>

<gadget id="calculator">60 / 2</gadget>
<output>30</output>

<gadget id="calculator">30 + 60</gadget>
<output>90</output>

<gadget id="calculator">90 / 6</gadget>
<output>15</output>

<result>15</result>