A batch of goods is shipped in three times, the first time it is all (3/10), the second time it is 3 tons more than the first time, and the third time it is 20% of the total, how many tons is this batch of goods in total? ?
一批货物分三次运完，第一次运走全部的(3/10)，第二次比第一次多运了3吨，第三次运了全部的20%，这批货物共有多少吨？
<gadget id="calculator">3 / 10</gadget>
<output>3/10 = around 0.3</output>

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

<gadget id="calculator">1 - (3/10) - (3/10) - (1/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">3 / (1/5)</gadget>
<output>15</output>

<result>15</result>