Answer
The equivalent interval notation is (4,6).
Work Step by Step
$-11$ $\gt$ $- 3x + 1$ $\gt$ $- 17$
$- 11 - 1$ $\gt$ $- 3x$ $\gt$ $- 17 - 1$
$\frac{-12}{-3}$ $\lt$ $x$ $\lt$ $\frac{-18}{-3}$ (Inequality sign reversed because of multiplication of -3)
$4$ $\lt$ $x$ $\lt$ $6$
The equivalent interval notation is (4,6).