Departments A, B, C, and D Need to Be Assigned

Departments A, B, C, and D need to be assigned to four rooms 1, 2, 3, and 4. These rooms are arranged in a row, in that order, with 20 meters between each. The departmental work flows are contained in the table below.
a. What is the material handling total of assigning A-1, B-2, C-3, D-4?
b. What is the material handling total of assigning A-1, B-3, C-4, D-2?
Flow Matrix
$$\begin{array} { | c | c | c | c | c | } \hline & \text { Dept. A } & \text { Dept. B } & \text { Dept. C } & \text { Dept. D } \\\hline \text { Dept. A } & 0 & 30 & 5 & 20 \\\hline \text { Dept. B } & 5 & 0 & 40 & 20 \\\hline \text { Dept. C } & 0 & 10 & 0 & 40 \\\hline \text { Dept. D } & 10 & 5 & 0 & 0 \\\hline\end{array}$$