There are 40 tons of cement on the construction site, 3 tons are used for the first time, and 800 kg are used for the second time. How much cement is left?
工地上有40吨水泥，第一次用去3吨，第二次用去800千克，还剩多少水泥？
<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>