Pull a batch of bricks from the construction site, pull them on the first day (2/5), and pull 20,000 pieces on the second day, leaving 20% of the bricks. How many bricks are there in total?
工地拉一批砖，第一天拉来(2/5)，第二天拉来2万块，还余这批砖的20%．这批砖共多少块？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">20 / 100</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">2 / (2/5)</gadget>
<output>5</output>

<result>5</result>