The number A is 7.5, which is exactly 30% of the number B. What is the number B?
甲数是7.5，正好是乙数的30%，乙数是多少．
<gadget id="calculator">30 / 100</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">7.5 / (3/10)</gadget>
<output>25</output>

<result>25</result>