Answer:
27
Step-by-step explanation:
If S-A-D (S, A, D are collinear)
Then:
[tex]SD = SA + AD\\
\therefore 4x + 7 = 5x - 8 + 2x\\
\therefore 4x + 7 = 7x - 8\\
\therefore 4x - 7x = - 8 - 7\\
\therefore - 3x = - 15\\
\therefore x=\frac{-15}{-3}\\
\huge \purple {\boxed {\therefore x = 5}} \\
SD = 4x + 7\\
SD = 4\times 5+ 7 \\
SD = 20+ 7 \\
\huge \orange {\boxed {SD = 27}} \\[/tex]
