Use a car to transport a batch of materials to the disaster area, transport away the total (2/5) for the first time, and transport the rest (1/3) for the second time, and there are still 20 tons left. How many tons are there in total?
用汽车将一批物资运往灾区，第一次运走总数的(2/5)，第二次运走余下的(1/3)，这时还剩下20吨．这批物资一共有多少吨？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

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

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

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

<result>50</result>