The second of these should be y=200/0.04=5000. Which gives the

critical points at (57.735,5000) and (-57.735,5000). Neither of these

are in the feasible region.

As the constraints are of strict inequality type there is no point in

the faesible region at which R(x,y) takes a maximal value.

If the constraints were:

x>=0, y>=0, and 8x+3y<=2400,

then the maximum would occur on the boundary of the feasible region, and

one could find it by examining R(x,y) on the boundary.

RonL