A pile of yellow sand was transported away on the first day (4/12) and on the second day (5/12). What fraction of the sand was transported in total in two days? How much of this pile of yellow sand is left unlucky?
一堆黄沙，第一天运走它的(4/12)，第二天运走它的(5/12)，两天共运走了这堆沙的几分之几？这堆黄沙还剩几分之几没运？
<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">1 - (3/4)</gadget>
<output>1/4 = around 0.25</output>

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