Using the combined gas law, where PV/T = constant, we first solve for PV/T for the initial conditions: (4.50 atm)(36.0 mL)/(10.0 + 273.15 K) = 0.57213. Remember to use absolute temperature. For the final conditions: (3.50 atm)(85.0 mL)/T = 297.5/T Since these must equal, 0.57213 = 297.5/T T = 519.98 K Subtracting 273.15 gives 246.83 degC.