A batch of coal is planned to burn 0.6 tons per day, and it can be burned for 70 days. If 0.04 tons are saved every day, how many days can it be burned?
一批煤计划每天烧0.6吨，可烧70天，如果每天节约0.04吨，这样可以烧多少天？
<gadget id="calculator">0.6 * 70</gadget>
<output>42</output>

<gadget id="calculator">0.6 - 0.04</gadget>
<output>0.56</output>

<gadget id="calculator">42 / 0.56</gadget>
<output>75</output>

<result>75</result>