Parabola

We have the form

x =  a ( y - k)^2 + h          where the vertex is  (h , k)

Since the point   (2,0)  is on the  graph

2  =  a ( 0 -  -1)^2  + 4

2 - 4  = a *1

-2 = a

So

x =  -2 ( y + 1)^2  + 4

x =  -2 ( y^2 + 2y + 1) + 4

x = -2y^2 - 4y - 2 + 4

x = -2y^2 - 4y + 2

x = ay^2 + by + c

a = -2   b = -4     c = 2

a + b + c  =   

-4