Chemical Kinetics

The rate of reaction $\text{A} + \text{B} \rightarrow \text{P}$ is $4 \times 10^{-2}\ \text{mol dm}^{-3}\ \text{s}^{-1}$
When $[A] = 0.2\ \text{mole dm}^{-3}$ and $[B] = 0.1\ \text{mole dm}^{-3}$, What is the rate constant of reaction, if it is first order with respect to A and second order with respect to B ?