The store bought a batch of new trench coats, sold 20% of the total number on the first day, and 45% of the total number on the second day, and sold a total of 260 pieces in two days. How many pieces of this batch of windbreakers were there?
商店购进一批新款风衣，第一天卖出总数的20%，第二天卖出总数的45%，两天一共卖了260件，这批风衣原有多少件？
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">45 / 100</gadget>
<output>9/20 = around 0.45</output>

<gadget id="calculator">(1/5) + (9/20)</gadget>
<output>13/20 = around 0.65</output>

<gadget id="calculator">260 / (13/20)</gadget>
<output>400</output>

<result>400</result>