Linear Programming

$$\displaystyle \left ( x+y \right )\left ( dx-dy \right )= dx+dy.$$
$$\displaystyle \left ( x+y \right )\left ( dx-dy \right )= dx+dy.$$
Solve the following Linear Programming Problems graphically:
Minimise $$Z = -3x + 4y$$
subject to $$x + 2y\leq 8, 3x + 2y \leq 12, x\geq 0, y \geq 0$$.