hello ....
the equation of a plane that is ; ax+by+cz +d =0
the vector perpendicular to this plane is : V(a,b,c)
in this exercice ; a = -4 b= -4 c = -1
then: the equation of a plane that is ; -4x-4y-z +d =0
but the plane passing through the point (−2,−5,5) :
-4(-2)-4(-5)-(5) +d =0
23+d =0
d =-23
the equation of a plane is : -4x-4y-z-23 =0
