A chicken and a rabbit are in the same cage. The chicken heads are 20 more than the rabbit heads, and the rabbit feet are 200 more than the chicken feet. How many chickens and rabbits are there in total?
鸡兔同笼，鸡头比兔头多20只，兔脚比鸡脚多200只，鸡、兔共有多少只．
<gadget id="calculator">20 * 2</gadget>
<output>40</output>

<gadget id="calculator">40 + 200</gadget>
<output>240</output>

<gadget id="calculator">4 - 2</gadget>
<output>2</output>

<gadget id="calculator">240 / 2</gadget>
<output>120</output>

<gadget id="calculator">120 + 20 + 120</gadget>
<output>260</output>

<result>260</result>