The construction site transports (5/7) tons of yellow sand, (2/5) is used on the first day, and (1/4) is used on the second day, how much is left?
建筑工地运来(5/7)吨黄沙，第一天用去它的(2/5)，第二天用去它的(1/4)，还剩多少？
<gadget id="calculator">5 / 7</gadget>
<output>5/7 = around 0.714286</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

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

<gadget id="calculator">1 - (2/5) - (1/4)</gadget>
<output>7/20 = around 0.35</output>

<gadget id="calculator">(5/7) * (7/20)</gadget>
<output>1/4 = around 0.25</output>

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