There are 280 cattle on the farm, the number of pigs is 2/5 of that of cattle, and 70% of that of sheep. How many sheep are there on the farm?
农场有牛280头，猪的头数是牛的(2/5)，又是羊的70%，农场养羊多少只．
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">70 / 100</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">(2/5) / (7/10)</gadget>
<output>4/7 = around 0.571429</output>

<gadget id="calculator">280 * (4/7)</gadget>
<output>160</output>

<result>160</result>