From the solution of
Problem 319:
Maximum T
br = 4.970 kN·m
Maximum T
st = 1.963 kN·m
$\theta_{br} = \theta_{st}$
$\left( \dfrac{TL}{JG} \right)_{br} = \left( \dfrac{TL}{JG} \right)_{st}$
$\dfrac{4.973a(1000^2)}{\frac{1}{32}\pi (75^4)(35\,000)} = \dfrac{1.963b (1000^2)}{\frac{1}{32}\pi (50^4)(83\,000)}$
$b/a = 1.187$
$T = T_{br \, max} + T_{st \, max}$
$T = 4.970 + 1.963$
$T = 6.933 \, \text{kN}\cdot\text{m}$ answer