Find elongation of the bar which is subjected to axial loads

Finding total elongation of the bar subjected to axial loads.
Please comment if you have any doubts.

[vishalmishra]

2nd part is wrong its need to be 30 kn. 80kn-50kn=30kn & -20-10kn which is also 30kn from backward direction.

[raviravindran]

In point CD
We obtain change in length with given load and area we get 0.114 mm
But in video there is 0.20mm