Forces and equilibrium — practice question

A car with mass $1250\,\text{kg}$ moves on a straight horizontal road while its engine delivers power at a steady rate of $P\,\text{W}$. The resistive force opposing the car’s motion remains constant and has magnitude $R\,\text{N}$. At a speed of $19\,\text{m s}^{-1}$, its acceleration is $0.6\,\text{m s}^{-2}$, and at a speed of $30\,\text{m s}^{-1}$, its acceleration is $0.16\,\text{m s}^{-2}$.