Please write out this vector as <−8, 8, 4>. The unit vector that has the same direction as this is found by dividing <−8, 8, 4> by the magnitude of <−8, 8, 4>.
This magnitude is √(64+64+16) = √144 = 12.
Thus, the desired unit vector is (1/12)<−8, 8, 4>.
