There are 2007 cattle and buffaloes in the cattle farm, including 1105 cows, 1506 cattle and 200 male buffaloes. How many female cattle are there?
养牛场有2007头黄牛和水牛，其中母牛1105头，黄牛1506头，公水牛200头，那么母黄牛有多少头．
<gadget id="calculator">2_007 - 1_506</gadget>
<output>501</output>

<gadget id="calculator">501 - 200</gadget>
<output>301</output>

<gadget id="calculator">1_105 - 301</gadget>
<output>804</output>

<result>804</result>