How many moles of a gas are in a 2.2-liter balloon at 600 mmHg and 85 C. Also asks to identify the P, V, N, R, and T. If unknown then put "?"

P = 600 mmHg
V = 2.2 L
T = 85°C
R = 0.08206 L atm / mol K
n = ?

I would start by converting the P from mmHg to atm, since our gas constant R uses atm.

600 mmHg • 1 atm / 760 mmHg = 0.789 atm = P

Then I would convert T from Celsius to Kelvin, since our gas constant R uses Kelvin.

85 + 273 = 358 K

Now you can solve PV = nRT for n, giving you:
n = PV/RT
n = (0.789 atm)(2.2 L) / (0.08206 L atm / mol K)(358 K) = 0.059 moles of gas