We have a line segment like this:
We can write:
[tex]\begin{gathered} SU=ST+TU \\ 4x+1=(3x-1)+(3x) \\ 4x+1=6x-1 \\ 4x-6x=-1-1 \\ -2x=-2 \\ x=\frac{-2}{-2} \\ x=1 \end{gathered}[/tex]
Then, we can find SU as:
[tex]SU=4x+1=4\cdot1+1=4+1=5[/tex]
Answer: SU = 5
