You're missing a negative sign
EDIT: My bad I read the question wrong. I have edited my answer accordingly.
Came up with the answer 2/3 + 2/3i
What am I doing wrong? It's showing up as incorrect.
Your answer, , is correct.
If you entered your answer as 2/3 + 2/3i,
. . it might be read as:
Try entering it as. 2/3 + 2i/3. or .2/3 + (2/3)i.