Solve the equation: 80x+80(x-3)=2640.
解方程：80x+80(x-3)=2640．
<gadget id="calculator">80 * 3</gadget>
<output>240</output>

<gadget id="calculator">240 + 2_640</gadget>
<output>2_880</output>

<gadget id="calculator">80 + 80</gadget>
<output>160</output>

<gadget id="calculator">2_880 / 160</gadget>
<output>18</output>

<result>18</result>