A line parallel to the given two lines would be of the form x+2y+a=0
And a line perpendicular to all three would be of the form y=2x+c..now solving this line with all three lines we get the points of intersection as..
With L1 : ((5-2c)/5,(10+c)/5)...let's say point A
With L2 : ((-9-2c)/5,(-36+2c)/5).....ptB
With x+2y+a=0 : ((-a-2c)/5, (-4a+2c)/10).......ptC
now ptB divides the line AC in the ration 1:6 internally ..
.: using section formula
(-a-2c)/5 = ((-9-2c)/5 + 6((5-2c)/5)) / 7
=>-7a-14c=-9+30-2c-12c
=>a=-3..
so the rqd line is x+2y-3=0...(ans)