If 2(x+3) and 3,1-x) are opposite numbers, what is the value of x
如果2(x+3)与3,1-x)互为相反数，那么x的值是多少
<gadget id="calculator">3 - 0</gadget>
<output>3</output>

<gadget id="calculator">6 + 3</gadget>
<output>9</output>

<gadget id="calculator">3 - 2</gadget>
<output>1</output>

<gadget id="calculator">9 / 1</gadget>
<output>9</output>

<result>9</result>