Your answer is incorrect.
Consider the points P = (1, 2, 9), Q = (3, 4, 23) and R = (-1, 2, 1).
Find a vector perpendicular to $\overrightarrow{PQ}$ and $\overrightarrow{PR}$ and then use it to find the equation of the plane which contains P, Q, and R.
ax + by + z = c, where a = 16 , b = 12 , c = -4