In a regular hexagon PQRSTU, Find the vector sum of PQ+PR+PS+PT+PU in terms of vector PO where O is the centre of hexagon

A hexagon is a six-sided figure inscribed within a circle.
The length of each side is that of the radius

Since the center is equidistant from all vertices,
and since each pair of opposing vertices lie opposite sides
of the center, P + S + Q + T + R + U = 0

Let O be the center, PQ = TS
SO = OP = -QR. Hence, TP = TS + SP = a - 2b
Likewise, UO = PQ and OP = -QR. Hence, UP = a - b