Question

Sally was able to drive

Answer 1

Remark
Average in this case does not mean you take (s1 + s2)/2. What average speed  means is Total Distance / Total Time.

Formula
Average speed(s) = Total Distance / Total Time

Givens
Total Distance = 252 + 30 = 282 miles
Total Time = 5 hours.

Substitute and Solve
Average speed = 282 / 5 
Average speed = 56.4 miles / hour <<<<< Answer.

The other facts are not used.