b$)$ When discussing linear indexing in Section $2\mathrm{.}4,$ we arrived the linear index in Eq$.(214)$

by inspection. The same argument used there can be extended to a $3-$D array with

coordinates $x,y,$ and $z,$ and corresponding dimensions $M,N,$ and $P.$ The linear index for

any $(x,y,z)$ is:

$s=x+M_{y+Nz}$ Start

with this expression and:

I. Derive Eq$.(2-15).$

II$.$ Derive Eq$.(2-16).$