Answer
Assuming that variables $a, b, c,$ and $d$ are stored in memory locations $100,$
$101,102,$ and $103,$ respectively:
$\begin{array}{llll}
{\text {Memory}} & {\text {} } & {\text {Address} } & {\text {} }\\
{\text {Location }} & {\text {Op Code} } & {\text {Field} } & {\text {Comment} }\\
{50} & {\text { LOAD }} & {100} & {\text { Register } R \text { now contains the value of } a} \\ {51} & {\text { SUBTRACT }} & {104} & {R \text { now contains the value } a-1} \\ {52} & {\text { STORE }} & {100} & {\text { Store the result into } a}
\end{array}\\$
Work Step by Step
Assuming that variables $a, b, c,$ and $d$ are stored in memory locations $100,$
$101,102,$ and $103,$ respectively:
$\begin{array}{llll}
{\text {Memory}} & {\text {} } & {\text {Address} } & {\text {} }\\
{\text {Location }} & {\text {Op Code} } & {\text {Field} } & {\text {Comment} }\\
{50} & {\text { LOAD }} & {100} & {\text { Register } R \text { now contains the value of } a} \\ {51} & {\text { SUBTRACT }} & {104} & {R \text { now contains the value } a-1} \\ {52} & {\text { STORE }} & {100} & {\text { Store the result into } a}
\end{array}\\$
