The sum of 4.1 and 4 times x is 18, what is x?
4.1与x的4倍的和是18，x是多少．
<gadget id="calculator">18 - 4.1</gadget>
<output>13.9</output>

<gadget id="calculator">13.9 / 4</gadget>
<output>3.475</output>

<result>3.475</result>