When it says back, I am assuming it is travelling in the opposite direction of the direction it just travelled, which was west.
So, the palne is at 47 mi north and 24 miles east of where it started. This makes a right triangle with sides 47 mi and 24 mi. The tangent of the angle between the north line and the line from where it is currently is equal to 24/47.
tanx = 24/47
x = 27 degrees (rounded to the nearest whole number) this is the angle the plane moved with respect to the north line. With re4spect to the ground, it will be 90 - 27 = 63 degrees