please help need asap

A standard 0.50 in orifice is installed in a 2-in schedule 40 pipe. Dry air (Cp/Cv = 1.4) at upstream conditions of 80F and 20 psig flows through the orifice at such a rate that a U-tube manometer connected across the taps indicates a reading of 40 cm of oil. The oil has a specific gravity of 0.83. (a) Calculate the volumetric flow rate of air at STP. (b) What is the power consumption of the meter