Answer
$[-\dfrac{7}{3},1]$
Work Step by Step
Given: $|-1+3(x+1)| \leq 5$
or, $-5 \leq -1+3x+3 \leq 5$
or, $-5\leq 3x+2 \leq 5$
or, $-5-2\leq 3x \leq 5-2$
or, $-7\leq 3x \leq 3$
or, $-\dfrac{7}{3}\leq x \leq 1$
Hence, $[-\dfrac{7}{3},1]$