and B start from two places AB at the same time, and travel towards each other at a constant speed. When A and B meet at C on the way, C starts from B and goes to A at a constant speed. When A and C meet at D, A immediately turns around and the speed drops to 80% of the original speed. When A and C start from A at the same time, B is still 720 meters away from A. If the distance between CD is 900 meters, how many meters is the distance between A and B?
甲、乙两人分别从AB两地同时出发，相向匀速而行，当甲、乙在途中C地相遇时，丙从B地出发，匀速去A地，当甲与丙在D地相遇时，甲立即调头且速度降为原来的80%，当甲、丙同时从A地时，乙离A地还有720米，如果CD间的路程是900米，那么AB间的路程是多少米？
<gadget id="calculator">900 + 720</gadget>
<output>1_620</output>

<gadget id="calculator">4 + 9</gadget>
<output>13</output>

<gadget id="calculator">13 / 4</gadget>
<output>13/4 = around 3.25</output>

<gadget id="calculator">1_620 * (13/4)</gadget>
<output>5_265</output>

<result>5_265</result>