Algebra

The one and only vaule for a is -3

a/3  + 1  = a + 3

1 - 3  =   a - a/3

1 - 3  =  (2/3)a

-2  =  (2/3) a

(3/2)(-2) = a

-3  =  a    {  just as figlavaplanet  found  !!!  }