Final answer:
The displacement of the motorbike rider is 30 miles east, which is calculated by subtracting the westward distance from the eastward distance traveled by the rider.
Step-by-step explanation:
The displacement of an object is defined as its change in position from its starting point to its ending point, measured along a straight line and in a specified direction. To calculate the net displacement of the motorbike rider mentioned in the problem, one needs to consider the direction of the rider's movements. The rider initially travels 50 miles west, then turns around and travels 80 miles east. To find the net displacement, one subtracts the distance covered in the westward direction from the distance covered in the eastward direction:
Displacement = Eastward distance - Westward distance
Displacement = 80 miles - 50 miles
Displacement = 30 miles east
Therefore, the rider's net displacement is 30 miles east.