The Bureau of Radio, Film and Television wants to install set-top boxes for 840 households in the community. It has been installed for 12 days, an average of 45 households per day, and the rest will be installed in 6 days. How many households are installed per day on average?
广电局要给小区里的840户居民装机顶盒，已经装了12天，平均每天装45户，余下的要6天装完，余下的平均每天装多少户？
<gadget id="calculator">45 * 12</gadget>
<output>540</output>

<gadget id="calculator">840 - 540</gadget>
<output>300</output>

<gadget id="calculator">300 / 6</gadget>
<output>50</output>

<result>50</result>