Question

One morning, Justin drove 5 hours before stopping to eat lunch at chick-fil-A. After lunch, he increased his speedy by 10 mph. If he completed 310-mile trip in 9 hours of driving time, how fast did he drive in the morning?

Answer 1

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