Master Li has to make 350 parts, and completed (3/7) of the total in the first 3 hours. At this speed, how many hours will it take him to complete all the parts (column scale)
李师傅要做350个零件，前3小时完成了总数的(3/7)．照这样的速度，他完成全部零件需要多少小时(列比例式)
<gadget id="calculator">350 * 3</gadget>
<output>1_050</output>

<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">350 * (3/7)</gadget>
<output>150</output>

<gadget id="calculator">1_050 / 150</gadget>
<output>7</output>

<result>7</result>