Cars A and B start at the same time from A and B, which are 450 kilometers apart, and meet each other in 4.5 hours. It is known that car A travels 45 kilometers per hour, how many kilometers per hour does car B travel?
甲、乙两车同时从相距450千米的A、B两地相对出发，4.5小时两车相遇．已知甲车每小时行45千米，乙车每小时行多少千米？
<gadget id="calculator">450 / 4.5</gadget>
<output>100</output>

<gadget id="calculator">100 - 45</gadget>
<output>55</output>

<result>55</result>