The students were doing exercises. There were 9 people in front of Xiaowei and 10 people behind him. He stood in the 5th row from the left and the 15th row from the right. How many students do exercises in total?
同学们做操，小伟的前面有9人，后面有10人，他站在了左起第5行，右起第15行．做操的同学一共有多少名？
<gadget id="calculator">9 + 10 + 1</gadget>
<output>20</output>

<gadget id="calculator">15 - 1</gadget>
<output>14</output>

<gadget id="calculator">5 + 14</gadget>
<output>19</output>

<gadget id="calculator">20 * 19</gadget>
<output>380</output>

<result>380</result>