If a_1, a_2, a_3 … … and b_1, b_2, b_3 … … are A.P., and a_1=2, a_10=3, a_1 b_1=1=a_10 b_10, then a_4 b_4 is equal to -

If $\displaystyle a_1, a_2, a_3 \ldots \ldots$ and $\displaystyle b_1, b_2, b_3 \ldots \ldots$ are A.P., and $\displaystyle a_1=2, a_{10}=3, a_1 b_1=1=a_{10} b_{10}$, then $\displaystyle a_4 b_4$ is equal to -