There are 4 tons of cement on the construction site, 3 tons are used for the first time, and 800 kilograms are used for the second time. How many kilograms of cement are left?
工地上有4吨水泥，第一次用去3吨，第二次用去800千克，还剩下多少千克水泥？
<gadget id="calculator">800 / 1_000</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">40 - 3 - (4/5)</gadget>
<output>181/5 = around 36.2</output>

<result>181/5 = around 36.2</result>