What is the answer to - 1/3 (x+6)=0

For this all you need to do is isolate the x, you can do this by first multiplying both sides by -3 which would result in:

x+6 = 0

From here you can now subtract each side by 6 to isolate the x and you would get:

x=-6

You can double check your answer by plugging it back in!