The cement factory plans to produce a batch of cement. In the first month, 30% of this batch of cement was completed, and in the second month, 45 tons were produced. At this time, the remaining (2/5) of this batch of cement has not been produced. How many tons is this batch of cement?
水泥厂计划生产一批水泥，第一个月完成了这批水泥的30%，第二月生产了45吨，这时还剩下这批水泥的(2/5)没生产．这批水泥共有多少吨？
<gadget id="calculator">30 / 100</gadget>
<output>3/10 = around 0.3</output>

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

<gadget id="calculator">1 - (3/10) - (2/5)</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">45 / (3/10)</gadget>
<output>150</output>

<result>150</result>