Rabun family travel = 30 miles in 1/2 hours or in 30 minutes.
Therefore, in 1 hour Rabun family will travel = 2 × 30 = 60 miles.
Total number of miles they need to travel now = 75 miles.
75 miles = 60 miles + 15 miles.
60 miles traveled in 1 hour.
15 miles traveled in 1/4 hours or 15 minutes.
Total time taken to travel 75 miles = 1 hour 15 minutes.
Current time is 3:00 P.M.
After 1 hour and 15 minutes the time will be 4:15 P. M.