Forces and equilibrium — practice question

A car’s mass is $1000\,\text{kg}$. If it moves at a constant speed of $v\,\text{m s}^{-1}$, with $v>2$, the resistive force on the car is $(Av + B)\,\text{N}$, where $A$ and $B$ are constants. On a horizontal road, the car can maintain a steady speed of $18\,\text{m s}^{-1}$ when the engine output is $36\,\text{kW}$. It can also go up a hill making an angle of $\theta$ to the horizontal, with $\sin\theta = 0.05$, at a constant speed of $12\,\text{m s}^{-1}$ when the engine output is $21\,\text{kW}$.