y=(2/3)x in the tangent at the circle at the point G x+y=45 in-------> x+(2/3)x=45-------> (5/3)x=45------> x=45*3/5----> x=27 in y=45-x-----> y=45-27------> y=18 in
in the tangent at the circle at the point B z+y=39 z=39-y-------> z=39-18-----> z=21 in
in the tangent at the circle at the point F z+x=48 so 21+27=48 so 48=48------> is ok
