To calculate for the volume, we need a relation to relate the number of moles (n), pressure (P), and temperature (T) with volume (V). For simplification, we assume the gas is an ideal gas. So, we use PV=nRT.
PV = nRT where R is the universal gas constant
V = nRT / P
V = 65.5 ( 0.08205 ) (273.15 + 50.30) / 9.15
V = 189.98 L