using equation of continuity

            40 V_A = 20 V_B

Þ         2V_A = V_B

Using Bernoullies equation

${\mathrm{P}}_{\mathrm{A}}+\frac{1}{2}{\mathrm{\rho V}}_{\mathrm{A}}^2={\mathrm{P}}_{\mathrm{B}}+\frac{1}{2}{\mathrm{\rho V}}_{\mathrm{B}}^2$

$\Rightarrow {\mathrm{P}}_{\mathrm{A}}-{\mathrm{P}}_{\mathrm{B}}=\frac{1}{2}\mathrm{\rho }({\mathrm{V}}_{\mathrm{B}}^2-{\mathrm{V}}_{\mathrm{A}}^2)$

 $\Rightarrow \mathrm{\Delta P}=\frac{1}{2}1000({\mathrm{V}}_{\mathrm{B}}^2-\frac{{\mathrm{V}}_{\mathrm{B}}^2}{4})$

$\Rightarrow \mathrm{\Delta P}=500\times \frac{3{\mathrm{V}}_{\mathrm{B}}^2}{4}$

$\Rightarrow {\mathrm{V}}_{\mathrm{B}}=\sqrt{\frac{\left(\mathrm{\Delta P}\right)\times 4}{1500}}=\sqrt{\frac{\left(700\right)\times 4}{1500}}\mathrm{m}/\mathrm{s}$

Volume flow rate = 20 × 100 × V_B = 2732 cm³/s