The number A is 9.5, which is 2.5 less than 40% of the number B. Find the number B.
甲数是9.5，比乙数的40%少2.5，求乙数．
<gadget id="calculator">9.5 + 2.5</gadget>
<output>12</output>

<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">12 / (2/5)</gadget>
<output>30</output>

<result>30</result>