I need the answer as soon as possible

a = Consider a sealed, flexible balloon with a diameter of 6 m, filled with helium gas (R = 2077 J/kg-K) at a pressure and temper- ature of 689 kPa and 288 K, respectively. If the balloon expands to a diameter of 9 m, what is the final pressure and the work done by the gas in the expansion, assuming the process is isothermal? Assume that the helium is an ideal gas