We are given the following segment:
Since the total length of the segment is RT and "S" is between R and T this means that the sum of RS and ST must be RT, therefore, we have:
[tex]RS+ST=RT[/tex]
Now, we substitute the values of each segment:
[tex]x+3+5x=57[/tex]
Now, we add like terms:
[tex]6x+3=57[/tex]
Subtracting 3 from both sides:
[tex]\begin{gathered} 6x+3-3=57-3 \\ 6x=54 \end{gathered}[/tex]
now, we divide both sides by 6:
[tex]x=\frac{54}{6}=9[/tex]
Therefore, the value of "x" is 9.
