Please help me solve this problem

4-10. For sonic flow through a hole, the mass flow rate is a function of the upstream pressure only. This can be used to design a flow meter with the unique feature that the flow is not affected by downstream pressure fluctuations. A laboratory experiment requires a constant mass flow rate of methane of 0.1 g/s. What is the largest hole diameter (in mm) required to just produce sonic conditions at this flow rate? Of course, sonic flow conditions will occur at any hole diameter smaller than this. Assume the methane is available at a regulated pressure of 10 barg, an ambient pressure of 1 atm and a temperature of 25C