Solve the equation: 3,7.25-x)=8.1.
解方程：3,7.25-x)=8.1．
<gadget id="calculator">8.1 / 3</gadget>
<output>2.7</output>

<gadget id="calculator">7.25 - 2.7</gadget>
<output>4.55</output>

<result>4.55</result>