i try this one but graphmatica gives me different graph. Please help.
Solve for y in terms of x and replace y with the function notation f(x).
-2x + 5y = 9
5y = 2x + 9
y = (2/5)x + 9/5
or
y = (2x + 9)/5
now write f(x) = ...
either of the two versions, both are correct