$x - 4 = 3$ or $x - 4 = -3$

$x = 1$ or $7$

Add $3$ to both sides.
This problem should look familiar now.

Can the absolute value of anything ever equal a negative number?

Take the square root of both sides. You should now have two equations,
$x - 4 = 3$ and $x - 4 = -3$
This looks a lot like part (a).

Add $9$ to both sides. Now follow the same steps as in part (d).

Can you square any real number and get a negative result?