If 16.2*((4-x)/1)=8.1, find x=?
若16.2*((4-x)/1)=8.1，求x=？
<gadget id="calculator">16.2 * 4</gadget>
<output>64.8</output>

<gadget id="calculator">64.8 - 8.1</gadget>
<output>56.7</output>

<gadget id="calculator">16.2 * 1</gadget>
<output>16.2</output>

<gadget id="calculator">56.7 / 16.2</gadget>
<output>3.5</output>

<result>3.5</result>