Question

12 times square root of (z-1)= 3 times the square root of (3z+1050)

Answer 1

12*sqrt(z-1) = 3*sqrt(3z+1050).

Square both sides:
144(z-1) = 9(3z+1050).
144z - 144 = 27z + 9450.
144z - 27z = 9450+144.
117z = 9594.
Z = 9594 / 117 = 82.