Calculate "the number A is 400, which is (1/5) of the number B, find the number B", what can be listed
计算"甲数是400，是乙数的(1/5)，求乙数"，可列式为多少
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">400 / (1/5)</gadget>
<output>2_000</output>

<result>2_000</result>