First, you solve for y in terms of x.
2x + 3y = 4
3y = 4 - 2x
y = 4/3 - (2/3)x
Now, replace "y" with "F(x)"
F(x) = 4/3 - (2/3)x
2x + 3y = 4
3y = 4 - 2x
y = 4/3 - (2/3)x
Now, replace "y" with "F(x)"
F(x) = 4/3 - (2/3)x