Master Li makes 18 parts per hour, and Master Wang makes 20 parts per hour. The two work at the same time and finish it in 11 hours. How many parts are there in this batch?
李师傅每小时做18个零件，王师傅每小时做20个零件，两人同时工作，11小时后完成，这批零件有多少个？
<gadget id="calculator">18 + 20</gadget>
<output>38</output>

<gadget id="calculator">38 * 11</gadget>
<output>418</output>

<result>418</result>