Geometry "Coordinates" Homework Help!?

This is just an application of the Pythagorean theorem. Distance = sqrt((x2 - x1)^2 + (y2 - y1)^2) = sqrt((-115-65)^2 + (170-70)^2) = sqrt((-180)^2 + 100^2) = sqrt(32400 + 10000) = sqrt(42400) = 205.913 miles. And 205.913 miles / 400 mph = 0.5148 hours. Finally, 0.5148 hours * 60 minutes/hour = 30.89 minutes, which rounds to 31 minutes.