Doubt with Somif or Somifs

hello good afternoon friends, I'm in need of one more help.
I have values ​​in two sheets that can be negative or positive. I need another spreadsheet to have the result of these values, with eosin or somases.
Thanks

Okay, I understand, but I need to inform in the debit/credit column, that is, when the two values ​​are negative they can be added, and when one is negative and the other deposit cannot. that's why I need a formula with two somase.

Change your formula: =SUMIF(Planilha2!C3,"<0")+SUMIF(Planilha3!C3,"<0")

I did this formula several times and it never matched, with yours it was perfect, thank you so much for helping me.