There is a batch of cement, 25% of which was transported in the morning and 12.5 tons in the afternoon. At this time, half of the cement is left. How many tons of this batch of cement were there?
有一批水泥，上午运走了25%，下午运走了12.5吨，这时正好还剩下水泥的一半，这批水泥原来一共有多少吨？
<gadget id="calculator">50 / 100</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

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

<gadget id="calculator">12.5 / (1/4)</gadget>
<output>50</output>

<result>50</result>