A batch of goods, its (3/5) is shipped away, and 20 kilograms are shipped in. At this time, the goods are the original (4/5), how many kilograms of this batch of goods?
一批货物，运走它的(3/5)，又运来20千克，这时的货物是原来的(4/5)，这批货物原有多少千克？
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">1 - (3/5)</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(4/5) - (2/5)</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">20 / (2/5)</gadget>
<output>50</output>

<result>50</result>