Align vertices

I’d like you to ask for help. I can not solve the problem of vertices. I need to align vertices to a line (see image10.jpg).

I tried Snap - Selection to Grid, but I get bad result. Then I tried to thicken the grid (Display - Grid Floor - Lines and Scale) but some vertices have been drawn to the top of the grid and some vertices to the down. I also tried Snap during Transform but there is still no good result. What can I do?

First , after having selected those vertices press S (to scale) then 0 (the number) then X or Y or Z (the axis you want to align those vertices too) , from your screenshot it should be Y .

Once done, press N to display the panel from the right, at the 1st tab “Transform”
At the category “Median” , change the X or Y or Z (again depending on which axis you’re moving those vertices) to match the grid line you want them to be on.
From your screenshot again, it is the Y number you’ll need to change.

Thank you very much. It perfectly solved my problem.

Or scale all the verts on the Y axis to 0 and drag them into place.