Subtract the number itself from 5 times a number, the difference is 16.6, find the number.
一个数的5倍减去这个数自己，差是16.6，求这个数．
<gadget id="calculator">5 - 1</gadget>
<output>4</output>

<gadget id="calculator">16.6 / 4</gadget>
<output>4.15</output>

<result>4.15</result>