The rest center prepared food for 120 people for 30 days. 5 days later there are 30 new arrivals. How many days will the remaining food be enough?
休养所准备了120人30天的粮食．5天后有新来30人．余下的粮食还够用多少天？
<gadget id="calculator">120 * 30</gadget>
<output>3_600</output>

<gadget id="calculator">1 / 3_600</gadget>
<output>1/3_600 = around 0.000278</output>

<gadget id="calculator">(1/3_600) * 5 * 120</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">1 - (1/6)</gadget>
<output>5/6 = around 0.833333</output>

<gadget id="calculator">120 + 30</gadget>
<output>150</output>

<gadget id="calculator">(1/3_600) * 150</gadget>
<output>1/24 = around 0.041667</output>

<gadget id="calculator">(5/6) / (1/24)</gadget>
<output>20</output>

<result>20</result>