Ok to find the amount of moles of gas you have, you need to use the ideal gas law to solve this problem which is PV=nRT
P is pressure in atm
V is volume in Liters
n is the amount of substance (moles)
R is the ideal gas constant (0.0821)
T is the temperature (make sure its in kelvin) this will be 45+273= 318K
Now to solve plug the values into the equation
(5)(17) = n(0.0821)(318)
Now solve which will be:
85 = 26.1078n
Then you have to isolate the variable n by dividing both sides by 26.1078 which will get you a final answer of:
3.2557 moles (rounded)