Question 479008
In the North direction he has walked 4+12 = 16 miles
He has walked 12 miles in the eastern direction

From starting point to finishing point the distance is the hypotenuse
16 & 12 are the legs of a right triangle

d^2=16^2+12^2

d^2=256+144
d^2=400
d= 20 miles

He is 20 miles away from the start