Answer
$a=-15$ and $b=-7$
Work Step by Step
We are given:
$|x+4|\leq 2$
$-2\leq x+4\leq 2$
We subtract $4$:
$-6\leq x\leq-2$
And multiply by $2$:
$-12\leq 2x\leq-4$
And subtract $3$:
$-15\leq 2x-3\leq-7$
Therefore:
$a=-15$ and $b=-7$