converting standard form into vertex form

-z+4z=4

3z=4

z=4/3

Write in fraction.

You may use the app --Photomath 

Since you are looking for a vertex form, I assume you are starting with a QUADRATIC:
-z^2 + 4z =4

-z^2 +4z-4 = 0         we want     a(z-h)^2 +k =0   form

-1 (z^2 -4z +4) = 0    'complete the square'

-1  {(z-2)^2 +4 -4} = 0

-1 (z-2)^2 +0 = 0             is the vertex form   where vertex is 2, 0