[texhax] the best way to typeset

[Victor Ivrii]

I have the row of equalities with left/right sides of different
lengths, some fitting into single line and some not,  and I want to
typeset them as


A=         B
AAA =   BBBB
AAAAAAAAAAAA=
             BBBBBBBBBBBBBBB
AAAAAAAA=
             BBBBBBB


so that left hand expressions would be left-aligned and right-hand
expressions would be also left-aligned on "some tab" (automatically
chosen so the width of the whole thing  is just \linewidth)

Thank you in advance

Victor