A train covers 168 km in 4 hours. Find its speed.

42 km/hr

Explanation:

s = d/t (speed = distance/time)

s = 168/4

s = 42 km/hr

The Royal Society of London is an institution dedicated to the promotion of science, which was founded on November 28, 1660. At that time the truth was based on the authority of individuals or institutions, such as the absolutist monarchy and the Church. The Royal Society comes up with a motto contrary to this.