Passenger and freight trains are traveling towards each other from places A and B at the same time. It is known that it takes 5 hours for the passenger car to complete the journey. It is 1:3. According to this calculation, how many hours does it take for the truck to complete the journey?
客、货两车同时从A、B两地相向而行，已知客车行完全程需5小时，当客车行到两地的中点时，货车离中点的路程与客车已行路程的比是1：3．照这样计算，货车行完全程需多少小时？
<gadget id="calculator">5 / 2</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">(5/2) * 3</gadget>
<output>15/2 = around 7.5</output>

<result>15/2 = around 7.5</result>