We are going to use the ideal gas law, which states that
#PV=nRT#
#P# is the pressure in atmospheric pressures (for this case)
#V# is the volume in liters (for this case)
#n# is the number of moles of the substance
#R# is the gas constant
#T# is the temperature in Kelvin
Since our pressure is in atms, volume in liters, we have to use #R=0.082 l \ atm \ mol^-1 \ K^-1#.
Plugging in for #P=1.26atm#, #V=208l#, #n=9.95mol#, #R=0.082 l \ atm \ mol^-1 \ K^-1#, we get that
#1.26atm*208l=9.95mol*0.082l \ atm \ mol^-1 \ K^-1*T#
#T=(1.26atm*208l)/(9.95mol*0.082l \ atm \ mol^-1 \ K^-1)#
#T=(262.08cancel(atm) \ cancell)/(0.8159 cancel(mol) \ cancell \ cancel(atm) \ cancel(mol^-1) \ K^-1)#
#T=321.22/K^-1=321.22K#
We know that
#K="^@C+273.15#
#"^@C=K-273.15#
We know that #K=321.22#
#:."^@C=321.22-273.15=48.07~~48.1#
or
#T=48.1^@C#