A batch of goods, 15% of the first shipment, 18 boxes of the second shipment, 60% of the total volume, how many boxes of this batch of goods?
一批货物，第一次运走15%，第二次运走18箱，两次运走总量的60%，这批货物共有多少箱？
<gadget id="calculator">60 / 100</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">15 / 100</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">(3/5) - (3/20)</gadget>
<output>9/20 = around 0.45</output>

<gadget id="calculator">18 / (9/20)</gadget>
<output>40</output>

<result>40</result>