Answer:
30 mph
Step-by-step explanation:
Let the morning speed be represented by s.
Then the total distance drivern is 310 mi and this is equal to
5s + 4(s + 10):
5s + 4s + 40 = 310, or
9s = 270
Solving for s, we get s = 270/9 = 30
Then s + 10 = 40
He drove 30 mph in the morning and 40 mph in the afternoon.
Check: (30 mph)(5 hrs) + (40 mph)(4 hrs) = 310 miles. CORRECT