Master Li needs to produce 240 parts, and 100 parts are produced in 2.5 hours. According to this calculation, how many hours will it take to complete the task? (Answer with the knowledge of proportion)
李师傅要生产240个零件，2.5小时生产了100个，照这样的计算，还要多少小时才能完成任务？(用比例的知识解答)
<gadget id="calculator">240 - 100</gadget>
<output>140</output>

<gadget id="calculator">100 / 2.5</gadget>
<output>40</output>

<gadget id="calculator">140 / 40</gadget>
<output>7/2 = around 3.5</output>

<result>7/2 = around 3.5</result>