Subtract this number from 5 times of a number, the difference is 0.72, find this number.
一个数的5倍减去这个数，差是0.72，求这个数．
<gadget id="calculator">5 - 1</gadget>
<output>4</output>

<gadget id="calculator">0.72 / 4</gadget>
<output>0.18</output>

<result>0.18</result>