20 cows and 20 sheep will eat 20 tons of grass in 20 days. At this speed, how many tons of grass will 50 cows and 50 sheep eat in 50 days?
20头牛和20只羊一起，在20天里要吃20吨草，依这样速度，50头牛和50只羊在50天里要吃多少吨草．
<gadget id="calculator">20 / 20 / 20</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">(1/20) * 50 * 50</gadget>
<output>125</output>

<result>125</result>