Solve the equation: 4.2*3-3x=5.1.
解方程：4.2*3-3x=5.1．
<gadget id="calculator">4.2 * 3</gadget>
<output>12.6</output>

<gadget id="calculator">12.6 - 5.1</gadget>
<output>7.5</output>

<gadget id="calculator">7.5 / 3</gadget>
<output>2.5</output>

<result>2.5</result>