A truck drives from place A to place B. It travels 405 kilometers in 4.5 hours, and it is still 315 kilometers away from place B. According to this calculation, how many hours will it take to complete the journey? (Solve with ratio)
一辆货车从甲地开往乙地，4.5小时行驶了405千米，距乙地还有315千米，照这样计算，行完全程还要多少小时？(用比例解)
<gadget id="calculator">405 / 4.5</gadget>
<output>90</output>

<gadget id="calculator">315 / 90</gadget>
<output>7/2 = around 3.5</output>

<result>7/2 = around 3.5</result>