There are 400 tons of goods in the freight yard. The ratio of the first shipment to the total tonnage is 1:4, and the second shipment took away 20% of the total. How many tons are left?
货场里有400t货物，第一次运走的与总吨数的比是1：4，第二次运走了总数的20%，还剩多少吨？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/4) - (1/5)</gadget>
<output>11/20 = around 0.55</output>

<gadget id="calculator">400 * (11/20)</gadget>
<output>220</output>

<result>220</result>