There is a piece of grass that grows at a uniform rate every day. This piece of pasture can feed 100 cows for 3 weeks and 50 cows for 8 weeks. How many cows can feed for two weeks?
有一片牧草，草每天匀速的生长，这片牧草可供100头牛吃3周，可供50头牛吃8周，那么可供多少头牛吃两周？
<gadget id="calculator">100 * 3</gadget>
<output>300</output>

<gadget id="calculator">50 * 8</gadget>
<output>400</output>

<gadget id="calculator">400 - 300</gadget>
<output>100</output>

<gadget id="calculator">8 - 3</gadget>
<output>5</output>

<gadget id="calculator">100 / 5</gadget>
<output>20</output>

<gadget id="calculator">3 * 20</gadget>
<output>60</output>

<gadget id="calculator">300 - 60</gadget>
<output>240</output>

<gadget id="calculator">20 * 2</gadget>
<output>40</output>

<gadget id="calculator">240 + 40</gadget>
<output>280</output>

<gadget id="calculator">280 / 2</gadget>
<output>140</output>

<result>140</result>