Hello, I am new here and I could use some help. I got two alphabetic calculations

1)

ABC

X DE

---------

FGHD

CAAC

-------------

IDBDD

2)

ABCD : EF = FGH

?A

--

??

??

--

C?

??

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And letters are numbers 0-9. I really need to know how to solve it and I would like to know how it is done step by step.

Thanks