40% of a number plus 12 is just equal to the number itself. Find the number.
一个数的40%加上12正好等于这个数本身，求这个数．
<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">12 / (3/5)</gadget>
<output>20</output>

<result>20</result>