I NEED HELP WITH A CHEM QUESTION

Question

The 157 km trip takes 2.0 h. What was the average speed for the trip The return trip over the same route takes 3.0 h because of heavy traffic? What is the average speed for the return trip What is the average speed for the entire trip

Answer 1

Average speed is the distance/time so the average speed for the first part is (157 km)/(2.0 hr) = 78.5 km/hr which should be rounded to 79 km/hr since there are only 2 sig figs in the time.

The second leg has an average speed of 157/3 (I'll let you do the rest)

The average speed for the whole trip is (157 + 157)/(2 + 3) = 314/5 (I'll let you do the rest)