Question

(1,9) slope 5 y+a =5 (z-1) or y-a=5 (z+1) Or y-a=5 (z-1) or y-1=5 (2+a)

Answer 1

Do you mean (1,a) with slope 5
if so then
correct one should be

y - a = 5 (z - 1)

if a = 9 then
y - 9 = 5 (z - 1)

hope it helps