The school organized a spring outing. Xiaoying was late for some reason and missed the coach.

First correct it. The first one should be 80 kilometers per hour. How can it be 8 kilometers?

The answer is 72 kilometers per hour.

Let the speed be x km/h.

Equation: 80 *1.5-1.5x = 90 * (40/60)-(40/60) * x.