Vector Spaces & Bases · Hard problem

The vector $\mathbf w = (3, -3, 9)$ lies in the span of $\mathbf u = (-3, 3, 0)$ and $\mathbf v = (-2, 2, 3)$. Find the scalars $a, b$ with $\mathbf w = a\mathbf u + b\mathbf v$.