An engineering team used up a batch of cement (1/7) in January, and used up (1/4) of this batch of cement in February. How much of this batch of cement is left?
某工程队一月份用去一批水泥的(1/7)，二月份又用去这批水泥的(1/4)．这批水泥还剩下几分之几？
<gadget id="calculator">1 / 7</gadget>
<output>1/7 = around 0.142857</output>

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

<gadget id="calculator">1 - (1/7) - (1/4)</gadget>
<output>17/28 = around 0.607143</output>

<result>17/28 = around 0.607143</result>