There are 30 rows in the school auditorium. It is known that the first row has 15 seats, and each subsequent row has 2 more seats than the previous row. How many seats are there in total?
学校礼堂共有30排，已知第一排是15个座位，以后每排比前一排多2个座位，那么共有多少座位？
<gadget id="calculator">30 - 1</gadget>
<output>29</output>

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

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

<gadget id="calculator">15 + 73</gadget>
<output>88</output>

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

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

<result>1_320</result>