If the base sequence on a separated dna strand is cgtagg, what will the base sequence on its complementary strand be?

To determine what the base sequence for the complementary strand, would be simply remember the base pairing or nitrogenous base pairing rules, for which nitrogen containing base hydrogen bonds or complementary base pairs with another.

A = T
G = C

So the complementary strand would be :
GCATCC.

Yes they are correct good day