The school organized a spring outing for the students. Xiao Ming went up the mountain from A to B, crossed the top of the mountain and descended to B. He walked a total of 23.5 kilometers and took 6.5 hours. It is known that the uphill walk is 3 kilometers per hour, and the downhill walk is 5 kilometers per hour. How long will it take him to return to A from B via the original road and across the top of the mountain?
学校组织同学们春游，小明从甲地上山越过山顶下山到乙地，共走23.5千米，用6.5小时．已知上山每小时走3千米，下山每小时走5千米．他从乙地经原路上山越过山顶返回甲地，要用多少时间？
<gadget id="calculator">3 * 23.5</gadget>
<output>70.5</output>

<gadget id="calculator">97.5 - 70.5</gadget>
<output>27</output>

<gadget id="calculator">5 - 3</gadget>
<output>2</output>

<gadget id="calculator">27 / 2 / 3</gadget>
<output>9/2 = around 4.5</output>

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

<gadget id="calculator">23.5 - (27/2)</gadget>
<output>10</output>

<gadget id="calculator">10 / 5</gadget>
<output>2</output>

<gadget id="calculator">(9/2) + 2</gadget>
<output>13/2 = around 6.5</output>

<result>13/2 = around 6.5</result>