A liquid of density 750 kgm^$-$3 flows smoothly through a horizontal pipe that tapers in cross-sectional area from A₁ = 1.2 $\times$ 10^$-$2 m² to A₂ = ${{{A_1}} \over 2}$. The pressure difference between the wide and narrow sections of the pipe is 4500 Pa. The rate of flow of liquid is ___________ $\times$ 10^$-$3 m³s^$-$1.