Forces and equilibrium — practice question

A particle with mass $1.2\,\text{kg}$ rests on a rough plane inclined at an angle $\theta$ to the horizontal, where $\sin\theta = \frac{7}{25}$. It is maintained in equilibrium by a horizontal force of magnitude $P\,\text{N}$ acting in a vertical plane containing a line of greatest slope (see diagram). The coefficient of friction between the particle and the plane is $0.15$.