Find the Minimum Value of the Objective Function and Where

Multiple Choice

Find the minimum value of the objective function and where it occurs,subject to the indicated constraints. ​
Objective function:
​
Z = 10x + 4y
​
Constraints:
​
0 ≤ x ≤ 60
0 ≤ y ≤ 45
5x + 6y ≤ 420
​​ ​

A) Minimum at (0,0) : 0
B) Minimum at (60,20) : 680
C) Minimum at (0,45) : 180
D) Minimum at (60,0) : 600
E) Minimum at (30,45) : 480