Two people, A and B, start from A and B at the same time and walk towards each other at a constant speed. If each of them advances at a certain speed, they will meet each other in 4 hours. If each of them travels 1 km less per hour than the original plan , then meet in 5 hours, then how many kilometers is the distance between A and B?
甲、乙两人分别从A、B两地同时出发相向而行，匀速前进，如果每人按一定的速度前进，则4小时相遇，如果每人各自都比原计划每小时少走1千米，则5小时相遇，那么A、B两地的距离是多少千米？
<gadget id="calculator">5 - 4</gadget>
<output>1</output>

<gadget id="calculator">4 / 1</gadget>
<output>4</output>

<gadget id="calculator">1 * 2 * 4 * 5</gadget>
<output>40</output>

<result>40</result>