How do I align the numbers in the following table?

1512+6155 at
555+866 b
3788+4466 a
12512+55512 c

I need to align this set of data to look as follows:

1512+6155 at
555+866 b
3788+4466 a
12512+55512 c


I can left align or right align when I have the same number of characters,
but I struggle finding a solution when I need to align in 2 different places.
In the particular example, I need to align the +'s and the letter characters.

Thanks for your help!