Chapter 12: Vectors and the Geometry of Space - Section 12.5 - Lines and Planes in Space - Exercises 12.5 - Page 727: 27

$-20x+12y+z=7$

The standard equation of plane passing through the point $(a,b,c)$ is given as $p(x-a)+q(y-b)+r(z-c)=0$ The equation of normal to the plane; $n=\lt -20,12,1 \gt$ For point $(1,2,3)$, we get $(-20)(x-1)+(12)(y -2)+1(z-3)=0$ or, $-20x+20+12y-24+z-3=0$ Thus, $-20x+12y+z=7$