In a grid of wires, the temperature at exterior mesh points is maintained at constant values as shown in the figure. When the grid is in thermal equilibrium, the temperature at -128 each interior mesh point is the average of the temperatures at the four adjacent points. For instance, -129 11 T2 + 73 + 0 -120 Ti= 12 188 Find the temperatures Ti, T2, T3, T4, when the grid is in thermal equilibrium. T= T2 T3 = TA =