Answer
The equivalent interval notation is $(-3, 1)$.
Work Step by Step
$-7$ $\lt$ $2 + 3x$ $\lt$ $5$
$-7 - 2$ $\lt$ $3x$ $\lt$ $5 - 2$
$- \frac{9}{3}$ $\lt$ $x$ $\lt$ $\frac{3}{3}$
$-3$ $\lt$ $x$ $\lt$ $1$
The equivalent interval notation is $(-3, 1)$.