The number of A is 500, which is (2/5) of the number of B. What is the number of B?
甲数是500，是乙数的(2/5)，乙数是多少？
<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>