A ship travels between two ports, A and B, which are 120 kilometers apart. The speed of the downstream is 26 kilometers per hour, and the speed of the upstream is 18 kilometers per hour. The speed of a motorboat is 20 kilometers per hour. How many hours does it take for the motorboat to travel between the two ports?
一只轮船往返于相距120千米的甲、乙两港之间．顺流的速度是每小时26千米，逆流速度是每小时18千米．一艘汽艇的速度是每小时20千米．这艘汽艇往返于两港之间共需要多少小时．
<gadget id="calculator">26 - 18</gadget>
<output>8</output>

<gadget id="calculator">8 / 2</gadget>
<output>4</output>

<gadget id="calculator">20 + 4</gadget>
<output>24</output>

<gadget id="calculator">120 / 24</gadget>
<output>5</output>

<gadget id="calculator">20 - 4</gadget>
<output>16</output>

<gadget id="calculator">120 / 16</gadget>
<output>15/2 = around 7.5</output>

<gadget id="calculator">5 + (15/2)</gadget>
<output>25/2 = around 12.5</output>

<result>25/2 = around 12.5</result>