Hello, good afternoon, could someone explain these problems to me and put the formulas they used? :(

4) Let u = (2, 5, 2), V = i-2j + K, w = (1, 1, -2) calculate:

a) The value of z if 2 = 3u-2v + w

b) The unit vector in the z direction.

5) Calculate the angle between u and V. where u = (-3, 2,1) and v = (2i + 3j + k)

6) Obtain the projection of the vector V = (2,2, -1) on the vector w = (-2, -4, 4)

7) Determine the parametric equations of the line that passes through (0, 0,6) and that is parallel to V = -i + j - 2K

9) Obtain the area of the triangle whose vertices are the points P (1, -3, 4), Q (2,3, -1) and R (1, -3, -1)