I am doing a proof homework that requires this special composition. The equation numbers need to come before the equation, i.e. on the left of the equation. It should look something like this:
However, this was achieved rather hacky using tabto package and is not referenced (all numbers are typed in manually). Therefore, I was thinking if there is a way to put the equation number before the equations on the left in
align environment (or other similar environment for equations), so I could get automatic and referable equation numbers.