For any x and y, x⊙y=(x+y)/2, then 2007⊙2009=how many.
对于任何x和y都有x⊙y=(x+y)/2，那么2007⊙2009=多少．
<gadget id="calculator">2_007 + 2_009</gadget>
<output>4_016</output>

<gadget id="calculator">4_016 / 2</gadget>
<output>2_008</output>

<result>2_008</result>