$"$Q$3)$ Refrigerant$-134$a at $1$ MPa and $90C$ is to be cooled to $1$ MPa and $30C$ in a condenser by air. The air enters at $100$ kPa and $27C$ with a volume flow rate of $600\frac{m^3}{m}in$ and leaves at $95$ kPa and $60C.$ Determine the mass flow rate of the refrigerant.