Given a set of equations as below:

$\left[\begin{array}{cccc}-2\mathrm{.}6& 1& ?& ?\\ 1& -2\mathrm{.}6& 1& ?\\ ?& 1& -2\mathrm{.}6& 1\\ ?& 1& -2\mathrm{.}6& ?\end{array}\right]\left[\begin{array}{c}{T}_1\\ T_2\\ T_3\\ T_4\end{array}\right]=\left[\begin{array}{c}-240\\ 0\\ 0\\ -150\end{array}\right]$

Use hand calculation following Thomas algorithm $($TDMA$)$ algorithm to determine all the $P\text{'}$s and $Q\text{'}$s and solve for $T\text{'}$s$.$