The maximum value of $$z=7 x+8 y$$ subject to the constraints $$x+y \leq 20, y \geq 5, x \leq 10, x \geq 0, y \geq 0$$ is

For a feasible region OCDBO given below, the maximum value of the objective function $$z=3 x+4 y$$ is

The maximum value of $$z=3 x+5 y$$ subject to the constraints $$3 x+2 y \leq 18, x \leq 4, y \leq 6, x, y \geq 0$$, is

For the following shaded area, the linear constraints except $$x,y \ge 0$$ are