The construction site transports 500 tons of cement, and the cement transported is (2/5) of the river sand transported. How many tons of river sand are transported? (Write out the quantitative relationship first, and then list the solution to the equation.)
建筑工地运来500吨水泥，运来的水泥是运来的河沙的(2/5)，运来的河沙多少吨？(先写出数量关系，再列方程解．)
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">500 / (2/5)</gadget>
<output>1_250</output>

<result>1_250</result>