A straight-line L through the origin meets the lines `x+y=1` and `x+y=3` at P and Q respectively. Through P and Q two straight lines `L_(1)` and `L_(2)` are drawn, parallel to `2x-y=5` and `3x+y=5` , respectively. Lines `L_(1)` and `L_(2)` intersect at R, show that the locus of R as L varies, is a straight line