initial condition : Vi = 4.700 L , Ti = 71.0ºC +273 => 344 K
final condition : Vf = 3.300 L , Tf = ?
Pressure is constant:
According to charle's law , volume is directly proportional to temperature at constant pressure !
Hence Vi / Ti = Vf / Tf
4.700 L / 344 K = 3.300 L / Tf
Tf = 3.300 L * 344 K / 4.700 L
Tf = 1135200 / 4.700
Tf = 241.53 K
Tf = 241.53 - 273
Tf = -31.47ºC