Two electric toy cars, A and B, run opposite to each other from opposite ends of the track at the same time. Car A travels 5 cm per second, Car B travels 1 cm in the first second, 2 cm in the second second, 3 cm in the third second, ... , when the two cars meet, they travel the same distance. What is the length of the track in centimeters?
甲、乙两个电动玩具车同时从轨道的两端相对而行，甲车每秒行5厘米，乙车第一秒行1厘米，第二秒行2厘米，第三秒行3厘米，…，这样两车相遇时，走的路程相同．则轨道长多少厘米．
<gadget id="calculator">5 * 9 * 2</gadget>
<output>90</output>

<result>90</result>