JEE Advance - Mathematics (1997 - No. 4)

Let $$OA=a,$$ $$OB=10a+2b$$ and $$OC=b$$ where $$O,A$$ and $$C$$ are non-collinear points. Let $$p$$ denote the area of the quadrilateral $$OABC,$$ and let $$q$$ denote the area of the parallelogram with $$OA$$ and $$OC$$ as adjacent sides. If $$p=kq,$$ then $$k=$$.........