One mole of an ideal gas expands adiabatically from an initial state (T_A,V₀) to final state (T_f,5V₀). Another mole of the same gas expands isothermally from a different initial state (T_B,V₀) to the same final state (T_f,5V₀). The ratio of the specific heats at constant pressure and constant volume of this ideal gas is γ. What is the ratio T_A/T_B?