#### Answer

$y=34/9$

#### Work Step by Step

Recall, in order to cancel out a square root, we square both sides of the equation. Thus, we square both sides of the equation to obtain that 9(y-2)=16. We now simplify:
$9y-18=16 \\\\ 9y=34 \\\\ y=34/9$
We now must check our solution:
$3\sqrt{34/9-2}=4 \\\\ 3\sqrt{16/9} =4 \\\\ 3(4/3) =4 \\\\ 4=4$
This is true, so our solution is valid.