A batch of goods was originally planned to be transported 18 tons per day, and the shipment was completed in 15 days. The actual shipment was 20 tons per day. How many days was it actually shipped? (proportional solution)
一批货物，原计划每天运18吨，15天运完，实际每天运20吨，实际多少天运完？(比例解)
<gadget id="calculator">18 * 15</gadget>
<output>270</output>

<gadget id="calculator">270 / 20</gadget>
<output>27/2 = around 13.5</output>

<result>27/2 = around 13.5</result>