Question

A plane is 300 miles west of city​ A, and is flying west at 600 miles per hour. How long will it take for the plane to be 2490 miles west of city​ A?

Answer 1

The aircraft is already 300 miles west of A,
so it only has (2490 - 300) = 2190 more miles to go.

                        (2190 miles) / (600 miles/hour)

                   =  (2190 / 600) hours

                   =      3.65 hours

                   =        3 hours  39 minutes  more.