Lee R. answered • 10/27/15

Mathematics, physics, computer programming

total time, T, is 9:00 to 3:15 or 6.25 hours

time spent driving in the morning, M, is 150 miles / 57.8 mph = 2.6 hrs

time spent for lunch, L, is 90 minutes or 1.5 hours

if time spent driving in the afternoon is A, then

T = M + L + A

6.25 = 2.6 + 1.5 + A

6.25 = 4.1 + A

A = 2.15 = driving time in the afternoon

total distance to drive, D, is 280 miles

distance driven in the morning is 150 miles

Distance to drive in the afternoon is 280 - 150 = 130

speed needed to drive 130 miles in 2.15 hrs is 130miles/2.15hours = 60.5 mph