There are 15 seats in the first row of a movie theater, each subsequent row has 2 more seats than the previous row, and the last row has 73 seats. How many seats are there in total in this movie theater?
一个电影院的第一排有15个座位，以后每一排都比前一排多2个座位，最后一排有73个座位，这个电影院一共有多少个座位．
<gadget id="calculator">15 + 73</gadget>
<output>88</output>

<gadget id="calculator">73 - 15</gadget>
<output>58</output>

<gadget id="calculator">58 / 2</gadget>
<output>29</output>

<gadget id="calculator">29 + 1</gadget>
<output>30</output>

<gadget id="calculator">30 / 2</gadget>
<output>15</output>

<gadget id="calculator">88 * 15</gadget>
<output>1_320</output>

<result>1_320</result>