Let point A be [tex](0, 2)[/tex] and point B [tex](9, 0)[/tex]
[tex]m = \frac{y_2 - y_1}{x_2 - x_1} =\frac{0 - 2}{9 - 0} = \frac{-2}{9}[/tex]
Use the point-slope formula and whichever point you want as [tex](x_1, y_1)[/tex], in this case I'll use [tex](0, 2)[/tex]
[tex]y - y_1 = m(x - x_1)\\y - 2 = -\frac{2}{9}(x - 0)\\y -2 = -\frac{2}{9}x\\y = -\frac{2}{9}x + 2[/tex]