Two​ cars, 540 kilometers​ apart, begin driving toward each other on a​ long, straight highway. one car travels 75 kilometers per hour and the other 105 kilometers per hour. at the same​ time, a​ canary, starting on one​ car, flies back and forth between the two cars as they approach each other. if the canary flies 100 kilometers per hour and spends no time to turn around at each​ car, how far has it flown when the cars​ collide?