The school cafeteria bought a batch of coal and planned to burn 0.125 tons per day for 40 days. In fact, 20% of coal is saved every day, so how many days can it be burned? (answer with ratio)
学校食堂买来一批煤，计划每天烧0.125吨，可以烧40天．实际每天节约用煤20%，这样可以烧多少天？(用比例解答)
<gadget id="calculator">0.125 * 40</gadget>
<output>5</output>

<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">0.125 * (1/5)</gadget>
<output>0.025</output>

<gadget id="calculator">0.125 - 0.025</gadget>
<output>0.1</output>

<gadget id="calculator">5 / 0.1</gadget>
<output>50</output>

<result>50</result>