During the Dragon Boat Festival, Mingming’s family drove back to their hometown to visit their grandfather and grandma. The distance between their two families was 450 kilometers, and the car traveled 40% of the journey in the first 2 hours. At this speed, how many hours would it take them to reach their hometown? (Please think in multiple ways, one of which must be solved with proportional knowledge.)
端午节期间，明明一家开车回老家看望爷爷和奶奶，他们两家相距450千米，汽车前2小时行了全程的40%，照这样的速度，他们到老家需要几个小时？(请用多种方法思考，其中一种须用比例知识解决．)
<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(2/5) / 2</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">450 * (1/5)</gadget>
<output>90</output>

<gadget id="calculator">450 / 90</gadget>
<output>5</output>

<result>5</result>