Use the point-slope form of the equation of a line.
[tex] y - y_1 = m(x - x_1) [/tex]
[tex] y - 3 = -\dfrac{4}{3}[x - (-3)] [/tex]
[tex] y - 3 = -\dfrac{4}{3}(x + 3) [/tex]
[tex] 3(y - 3) = -4(x + 3) [/tex]
[tex] 3y - 9 = -4x - 12 [/tex]
[tex] 4x + 3y = -3 [/tex]