40% of the number A is the number B (2/3), the number A is 15, what is the number B?
甲数的40%是乙数的(2/3)，甲数是15，乙数是多少．
<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">(2/5) / (2/3)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">15 * (3/5)</gadget>
<output>9</output>

<result>9</result>