Forces and equilibrium — practice question

A small block with weight $5.1\,\text{N}$ is at rest on a smooth plane inclined at an angle $\alpha$ to the horizontal, where $\sin\alpha = \frac{8}{17}$. It is maintained in equilibrium by a light inextensible string. The string is inclined at an angle $\beta$ above the line of greatest slope on which the block rests, where $\sin\beta = \frac{7}{25}$ (see diagram).