I there a way to move multiple vertices preserving a straight line 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.
I can´t see in which axis you did the capture but for Option A I will assume it is a TOP VIEW so:
Select both of these RED circled vertex, now press S, SHIFT and DRAG to the RIGHT to scale them and make them align at SCALE 0 for both vertex.

If this is not what you expected, you can select and SLIDE the vertex you are interested by selecting the vertex and then press GG to move it

If this is still not what you expected, then select the vertex you want to align parpendicularly. Press X, D. Your vertex will be removed. Now, use the KNIFE (K) to make a clean cut from the appointed verted like in this graphic marked with the BLUE line as option 2.


Thanks for voting me up on this question or selecting it as your answer.

BFCT_Schiller