Master Zhang makes a batch of parts, and plans to make 40 parts per hour, which will be completed in 15 hours. Actually do 10 more per hour, how many hours to complete the task?
张师傅做一批零件，计划每小时做40个，15小时做完．实际每小时多做10个，实际多少小时完成任务？
<gadget id="calculator">40 + 10</gadget>
<output>50</output>

<gadget id="calculator">15 / 50</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">40 * (3/10)</gadget>
<output>12</output>

<result>12</result>