On the basis of the given data:
Volume (V) is 37.5 L
Temperature (T) is 307 K
Pressure (P) is 1.25 atm
In order to calculate the number of moles, the formula to be used is PV = nRT, Here R is 0.0821 Latm/mol/K
n = PV / RT
n = 1.25 atm × 37.5 L / 0.0821 Latm/mol/K × 307 K
n = 1.85 mol