Three Dimensional Geometry

If the plane $\bar{r} = (\lambda + \mu)\hat{i} + (2 + \mu)\hat{j} + (3\lambda + 2\mu)\hat{k}$, where $\lambda$ and $\mu$ are parameters, intersects coordinate axes at points $(a, 0, 0)$, $(0, b, 0)$ and $(0, 0, c)$ then $a + b + c = $...