Answer:
+9 or 12.464
Explanation:
We want to isolate the variable so we need to undo the right side.
First, take the square root on both sides: w-9=sqrt(12)
Then we add 9 to both sides: w=sqrt(12) + 9
w=sqrt(12)+9 would be the exact answer but if you want decimal, it would be approximately 12.464