I have a mesh where one side is tilted (marked red in the image):
What I want to do is move selected vertices along the red line so that bottom line (marked white in the image) remains straight.
When I move the selected vertices along the red line's local axis the bottoms line is getting bent in the middle.
What I want is to move the selected vertices and get the bottom line rotated as one straight line. I just worked around by adding another straight edge. rotating it, subdividing it in the middle and then replaced the old edge with the newly created one.
P.S. I didn't use the rotate tool since I wanted the two sides to remain straight.