Isothermal expansion beneath a balanced piston

An ideal gas containing $0.850\,\mathrm{kg}$ expands slowly and isothermally at $330\,\mathrm{K}$ until its volume is $2.70$ times the initial volume. Use $R=0.287\,\mathrm{kJ/(kg\,K)}$. Determine the boundary work performed by the gas, the change in internal energy and the heat transfer.