A small plane took off from Whitehorse to inspect a wildfire in the wilderness 255 kilometers away. Flying into the wind on the way out to the fire, the trip took 1.7 hours. Flying with the wind at its back, the plane only took 1.5 hours to return back to Whitehorse when it was done inspecting the fire. Determine the wind speed that day. a) Define the variables. b) Solve the problem.​