Jack drives at 40 mph for an hour, then at 50 mph for an hour.  What is his average speed?
Question:
Jack drives at 40 mph for an hour, then at 50 mph for an hour.  What is his average speed?
Answer:
Let's think step by step.

user
45\text{ mph}
Jack drives at 40 mph for an hour, then at 50 mph for an hour.  What is his average speed?
train