The children's theater has 30 rows of seats, 30 in the first row, 2 more seats in each row than the previous row, and 88 seats in the last row. How many seats are there in this theater?
儿童剧院有30排座位，第一排30个，后面每一排都比前一排多2个座位，最后一排有88个座位．这个剧院共有多少个座位？
<gadget id="calculator">30 + 88</gadget>
<output>118</output>

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

<gadget id="calculator">118 * 15</gadget>
<output>1_770</output>

<result>1_770</result>