The original batch of towels in Xintiandi Supermarket sold 40% of the total and then bought 240 new ones. At this time, the ratio of the total number of inventory to the original one is 2:3. How many original towels are there?
新天地超市原有一批毛巾，卖了总数的40%后又新进了240条，这时存货的总条数与原来的比是2：3，原有毛巾多少条？
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">(2/3) - (3/5)</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">240 / (1/15)</gadget>
<output>3_600</output>

<result>3_600</result>