There is a batch of goods in the market, 30% of the total amount was shipped on the first day, and 4 tons more than the total amount (1/5) was shipped on the second day. At this time, there are 20 tons left. How many tons are there in this batch of goods?
商场上有一批货，第一天运走了总数的30%，第二天运的比总数的(1/5)多4吨，这时还剩20吨，这批货物共有多少吨？
<gadget id="calculator">20 + 4</gadget>
<output>24</output>

<gadget id="calculator">30 / 100</gadget>
<output>3/10 = around 0.3</output>

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

<gadget id="calculator">1 - (3/10) - (1/5)</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">24 / (1/2)</gadget>
<output>48</output>

<result>48</result>