Explain how P was derived to be (0,-2,-3) in this question ? (Highlighted in YELLOW)

QUESTION:

Find an equation of the plane that is orthogonal to the plane 3x + 2y 42 = 7 and contains the line of intersection of the planes 2x 3y + z = 3 and x + 2y 32 = 5. Let P denote the required plane. The line L of intersection of the planes 2x 3y + z = 3 and x + 2y 32 = 5 must be perpendicular to the normal vectors of these planes; therefore, a direction of L is (2, 3,1)>