For a batch of goods, car A alone will be transported in 10 days, and car B will be transported in 15 days alone. How many days will it take for the two trucks to jointly transport this batch of goods (4/5) to complete the task?
一批货物，甲车单独运10天运完，乙车单独运15天运完．两车合运这批货物的(4/5)，多少天可完成任务？
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">(1/10) + (1/15)</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">(4/5) / (1/6)</gadget>
<output>24/5 = around 4.8</output>

<result>24/5 = around 4.8</result>