The synthetic division table is:
$$ \begin{array}{c|rr}5&-3&8\\& & \color{black}{-15} \\ \hline &\color{blue}{-3}&\color{orangered}{-7} \end{array} $$The solution is:
$$ \frac{ -3x+8 }{ x-5 } = \color{blue}{-3} \color{red}{~-~} \frac{ \color{red}{ 7 } }{ x-5 } $$Step 1 : Write down the coefficients of the dividend into division table. Put the zero from $ x -5 = 0 $ ( $ x = \color{blue}{ 5 } $ ) at the left.
$$ \begin{array}{c|rr}\color{blue}{5}&-3&8\\& & \\ \hline && \end{array} $$Step 1 : Bring down the leading coefficient to the bottom row.
$$ \begin{array}{c|rr}5&\color{orangered}{ -3 }&8\\& & \\ \hline &\color{orangered}{-3}& \end{array} $$Step 2 : Multiply by the number on the left, and carry the result into the next column: $ \color{blue}{ 5 } \cdot \color{blue}{ \left( -3 \right) } = \color{blue}{ -15 } $.
$$ \begin{array}{c|rr}\color{blue}{5}&-3&8\\& & \color{blue}{-15} \\ \hline &\color{blue}{-3}& \end{array} $$Step 3 : Add down last column: $ \color{orangered}{ 8 } + \color{orangered}{ \left( -15 \right) } = \color{orangered}{ -7 } $
$$ \begin{array}{c|rr}5&-3&\color{orangered}{ 8 }\\& & \color{orangered}{-15} \\ \hline &\color{blue}{-3}&\color{orangered}{-7} \end{array} $$Bottom line represents the quotient $ \color{blue}{ -3 } $ with a remainder of $ \color{red}{ -7 } $.