Marie traveled to work (7km) in 25 minutes. What was her speed?

Question

I got 16.8km/h but my teacher said it's 28km/h and I have no idea how he got that.

Also, how do you calculate average speed when there's more than one speed? (this is just for the next question)

Answer 1

7km/25min * 60min/hr = 420/25 km/hr = 16.8 km/hr

If he says the speed is 28km/hr, he's working on some other problem.

if there are various speeds, the average speed is the total distance divided by the total time.