The number A is 30 more than the number B, the difference is exactly (1/5) of the number B, what is the number B?
甲数比乙数多30，这个差恰好是乙数的(1/5)，乙数是多少．
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">30 / (1/5)</gadget>
<output>150</output>

<result>150</result>