The canteen of the cement factory brought back 3 tons of coal, which was planned to last for 20 days. After the stove was improved, the coal actually burned for 25 days. How many kilograms of coal is actually saved per day compared with the plan?
水泥厂食堂运回3吨煤，计划可以烧饭20天，改进炉灶后，这批煤实际烧了25天．实际平均每天比计划节约用煤多少千克？
<gadget id="calculator">1_000 / 20</gadget>
<output>50</output>

<gadget id="calculator">3 * 50</gadget>
<output>150</output>

<gadget id="calculator">1_000 / 25</gadget>
<output>40</output>

<gadget id="calculator">3 * 40</gadget>
<output>120</output>

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

<result>30</result>