How do I get two vertices in-line? (See img)

How do I get two vertices in-line?
On my roof, i need the extension the be in-line with the main body of the roof.


I am not sure from the image and description, I follow. But your answer is likely going to be in Transform Orientations.

select top edge of roof then CTrl Alt Space
and this will make new Transform for edge

then extrude bottom end of roof

don’t forget to change on bottom header back to global !

happy bl

Ok to clarify, I need to extrude fig1 so it lines up with fig 2


Ah! Got it now!

Can a Mod please prefix this topic to SOLVED please? TY