A piece of green grass on the grassland can be eaten by 70 cows in 24 days, and 30 cows can eat the grass in 60 days, so how many days will it take for 20 cows to eat the grass?
草原上的一片青草70头牛在24天内可以吃完这片草，30头牛在60天内可以吃完这片草，则20头牛吃完这片草的天数是多少．
<gadget id="calculator">30 * 60</gadget>
<output>1_800</output>

<gadget id="calculator">70 * 24</gadget>
<output>1_680</output>

<gadget id="calculator">1_800 - 1_680</gadget>
<output>120</output>

<gadget id="calculator">60 - 24</gadget>
<output>36</output>

<gadget id="calculator">120 / 36</gadget>
<output>10/3 = around 3.333333</output>

<gadget id="calculator">(10/3) * 24</gadget>
<output>80</output>

<gadget id="calculator">1_680 - 80</gadget>
<output>1_600</output>

<gadget id="calculator">20 - (10/3)</gadget>
<output>50/3 = around 16.666667</output>

<gadget id="calculator">1_600 / (50/3)</gadget>
<output>96</output>

<result>96</result>