Find the Minimum Value of the Objective Function and Where $$\left( 0 , \frac { 19 } { 6 } \right)$$

Find the minimum value of the objective function and where it occurs,subject to the constraints: ?
Objective function:
?
Z = 4x + 16y
?
Constraints:
?
X ? 0
Y ? 0
X + 4y ? 20
X + y ? 18
?2x + 2y ? 21
?

A) Minimum at $$\left( 0 , \frac { 19 } { 6 } \right)$$ : $$\frac { 152 } { 3 }$$
B) Minimum at $\left( \frac { 22 } { 3 } , 0 \right)$ : $\frac { 88 } { 3 }$
C) Minimum at (0,0) : 0
D) Minimum at $\left( \frac { 22 } { 3 } , \frac { 19 } { 6 } \right)$ : 80
E) No minimum