There are 20 rows of seats in a theater, the first row has 36 seats, and each rear row has 2 more seats than the previous row, how many seats are there in total in this theater?
一个剧场设置了20排座位，第一排有36个座位，后面每一排都比前一排多2个座位，这个剧场总共有多少个座位．
<gadget id="calculator">20 - 1</gadget>
<output>19</output>

<gadget id="calculator">19 * 2</gadget>
<output>38</output>

<gadget id="calculator">36 + 38</gadget>
<output>74</output>

<gadget id="calculator">36 + 74</gadget>
<output>110</output>

<gadget id="calculator">20 / 2</gadget>
<output>10</output>

<gadget id="calculator">110 * 10</gadget>
<output>1_100</output>

<result>1_100</result>