If a number is increased by 15%, it becomes 23. What is the number?
一个数增加15%以后是23，这个数是多少．
<gadget id="calculator">15 / 100</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">1 + (3/20)</gadget>
<output>23/20 = around 1.15</output>

<gadget id="calculator">23 / (23/20)</gadget>
<output>20</output>

<result>20</result>