For simplicity I'm going to call YEMEA1 = Y_1, YEMEA2=Y_2, Ydif = Yd, TEMA1 = T_1, TEMA2 = T_2, Tdiff = Td

The formula for T1 that you have can be simplified to , and .

If , then

Multiply numerator and denominator of the the left hand side by 6, and rearrange:

Note that Yd times Y_2 = Y_1, so:

Using your numbers above, where Y_1 = 4.28 and Y_d = 1.01905, you get Tp = 4.4495, T1 = 4.364752, T2 = 4.283168, and Td = 1.019048 (same as Yd).