A and B start from A and B respectively at the same time and walk toward each other. When they met, A ran 90 meters longer than B. After encountering, B's speed is reduced by 50%. After A arrives at B, he turns around immediately, and when he catches up with B, he is still 90 meters away from A. So, what is the distance between AB and AB?
甲、乙两人分别从A、B两地同时出发，相向而行．他们相遇时，甲比乙多跑90米．相遇后乙的速度减少50%，甲到B后立即调头，追上乙时离A还有90米．那么，AB间的路程为多少米．
<gadget id="calculator">3 - 2</gadget>
<output>1</output>

<gadget id="calculator">180 / 1</gadget>
<output>180</output>

<gadget id="calculator">2 * 180</gadget>
<output>360</output>

<gadget id="calculator">360 + 90</gadget>
<output>450</output>

<result>450</result>