Let the speed be x m/s. According to the meaning of the question,
△ABC is a right triangle with ∠C as the right vertex,
And BC=2x km, AC = 30m, AB = 50m.
Then (2x)? +30? =50?
The solution is x=20.
∴ The vehicle speed is 20m/s, that is, 72km/h > 70km/h.
The car was speeding.