Take into account that the Kinetic Molecular Theory establishes that Temperature is proportional to average kinetic energy.
Also take into account that the second Law of Thermodynamic states that the heat flow only from the higher temperature to the lower temperaure.
Then, the heat will transfer from the sample a to sample b if (and only if) the average kinecti energy of sample a's atoms is greater than the average kinetic energy of sample b's atoms.
