Answer :
To calculate the time it takes to complete a journey of 300 miles at different speeds, we can use the formula:
Time = Distance / Speed
(a) At 60 mph:
Time = 300 miles / 60 mph = 5 hours
(b) At 50 mph:
Time = 300 miles / 50 mph = 6 hours
(c) At 40 mph:
Time = 300 miles / 40 mph = 7.5 hours