Science Homework Help

A novice golfer on the green takes three strokes to sink the ball. The successive dis- placements are 6.8 m to the north, 5.8 m northeast, and 7 m 11◦ west of south. Start- ing at the same initial point, an expert (lucky) golfer could make the hole in a single displace- ment.
What is the magnitude of this single dis- placement?
Answer in units of m.