Pairwise Exchange Problem: Assuming Cij $=1$ along with using the From$/$To matrix and the layout provided $($moving from one block to an adjacent one is $10$ft; move from one block to a non$-$adjacent with rectilinearly$),$ answer the following questions:

What is the layout$$s D$-$Score?

Using departments $2,3,$ & $4,$ which pairwise exchange with department $1$ lowers the D$-$Score the most $($Enter the number of the department or $$none$$ if appropriate$)?$

What is the D$-$Score after that pairwise exchange?

From$/$To Matrix:

From$/$To

$1$

$2$

$3$

$4$

$5$

$6$

$1$

$50$

$20$

$30$

$10$

$15$

$2$

$35$

$10$

$20$

$15$

$3$

$25$

$45$

$10$

$4$

$10$

$30$

$5$

$45$

$6$