There is a batch of cement on the construction site. 35% of the total amount was removed on the first day, and 2/5 of the total amount was removed on the second day. There are still 28 tons left. How many tons of this batch of cement used to be?
工地有一批水泥，第一天运走总数的35%，第二天运走总数的(2/5)，还剩下28吨，这批水泥原有多少吨？
<gadget id="calculator">35 / 100</gadget>
<output>7/20 = around 0.35</output>

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

<gadget id="calculator">1 - (7/20) - (2/5)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">28 / (1/4)</gadget>
<output>112</output>

<result>112</result>