The students are doing exercises. Xiaoli is standing in the 9th row from the left and the 13th row from the right. There are 7 people in front of her and 17 people behind her. It is known that the number of people in each row and row is equal, how many students do exercises in total?
同学们做操，小丽站在左起第9行，右起第13行，她前面有7人，后面有17人．已知每行、每排人数分别相等，做操的同学一共有多少人？
<gadget id="calculator">13 - 1</gadget>
<output>12</output>

<gadget id="calculator">9 + 12</gadget>
<output>21</output>

<gadget id="calculator">17 - 1</gadget>
<output>16</output>

<gadget id="calculator">7 + 16</gadget>
<output>23</output>

<gadget id="calculator">21 * 23</gadget>
<output>483</output>

<result>483</result>