To determine Karla's average speed, you simply divide the total distance she traveled by the amount of time she spent traveling.
So first, you need to determine how many miles Karla drove. You do this by simply adding up the distances together.
486 miles + 316 miles + 638 miles = 1440 miles.
The may have taken 3 days for her trip, but during those 3 days, she only drove for 24 hours. So divide the distance by the time, giving:
1440 miles / 24 hours = 60 miles/hour.
