Answer
\begin{equation}
\begin{array}{|c|c|}\hline & {\text { Answer }} \\ \hline a & {1101} \\ \hline b & {0011} \\ \hline c & {1011} \\ \hline d & {1000} \\ \hline e & {1111} \\ \hline f & {0000} \\ \hline\end{array}
\end{equation}
Work Step by Step
\begin{equation}
\begin{array}{|c|c|}\hline & {\text { Answer }} & {\text { Reason }} \\ \hline a & {1101} & { because\ 5 + 8 = 13 → 1101\ } \\ \hline b & {0011} & { because\ -5 + 8 = 3 → 0011\ } \\ \hline c & {1011} & { because\ 3 + 8 = 11 → 1011\ } \\ \hline d & {1000} & { because\ 0 + 8 = 8 → 1000\ } \\ \hline e & {1111} & { because\ 7 + 8 = 15 → 1111\ } \\ \hline f & {0000} & { because\ -8 + 8 = 0 → 0000\ } \\ \hline\end{array}
\end{equation}
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you can see the image below: