The distance between A and B is 225 kilometers. A car travels from A to B at 45 kilometers per hour. How long does it take to reach B? (List the formulas containing the unknown x, and then solve it)
甲、乙两地相距225千米，一辆汽车从甲地开往乙地，每小时行45千米，到达乙地需要多少小时？(列出含有未知数x的算式，再解出来)
<gadget id="calculator">225 / 45</gadget>
<output>5</output>

<result>5</result>