Mingming read an extra-curricular book. He read 12 pages on the first day, then read 6 more pages every day than the previous day, and read 48 pages on the last day. How many days did he read in total?
明明读一本课外书，第一天读了12页，以后每天比前一天多读6页，最后一天读了48页，他共读了几天？
<gadget id="calculator">48 - 12</gadget>
<output>36</output>

<gadget id="calculator">36 / 6</gadget>
<output>6</output>

<gadget id="calculator">6 + 1</gadget>
<output>7</output>

<result>7</result>