In triangle PQR, right-angled at Q, with XY ∥ QR, if PQ is 6cm and PY is 4cm, and PX/XQ = 1:2, calculate the length of PR and QR.
a) PR = 3cm, QR = 6cm
b) PR = 4cm, QR = 8cm
c) PR = 5cm, QR = 10cm
d) PR = 6cm, QR = 12cm