There are two grasslands, A and B. The area of A is four times that of B. A group of cows ate together in A for a long time, and then they separated. Half of the cattle ate in A, and the other half ate in B, and ate for a long time. , The grass in B is finished. So how many days can the cows eat the remaining grass in Land A?
有甲乙两块草地，甲地面积是乙地的4倍，一群牛先一起在甲地吃了半天，后来它们分开，一半的牛在甲地吃，另一半在乙地吃，又吃了半天，乙地的草吃完了．那么甲地剩下的草可以让这群牛再吃几天？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/2) - (1/4)</gadget>
<output>1/4 = around 0.25</output>

<result>1/4 = around 0.25</result>