A pile of coal was originally planned to burn 4 tons per day, and it will be burned in 72 days. Now, 0.8 tons of coal is saved every day. How many days can it be burned? (Solve with ratio)
一堆煤，原计划每天烧4吨，72天烧完，现在每天节约用煤0.8吨，可以烧多少天？(用比例解)
<gadget id="calculator">4 * 72</gadget>
<output>288</output>

<gadget id="calculator">4 - 0.8</gadget>
<output>3.2</output>

<gadget id="calculator">288 / 3.2</gadget>
<output>90</output>

<result>90</result>