Xiaogang planned to do 15 math problems in 4 days, but he did 9 more. How much do you do on average per day?
小岗计划4天做15道数学题，结果多做了9道．平均每天做了多少道？
<gadget id="calculator">15 + 9</gadget>
<output>24</output>

<gadget id="calculator">24 / 4</gadget>
<output>6</output>

<result>6</result>