Answer:
If you mean the complementary strand of GAT: Answer is CTA
If you mean the strand for all of it (GATCCATGAGTTACG): Answer is CTAGGTACTCAATGC
Explanation:
Both strands always have to be in a sequence that pairs them to their nitrogenous base pair according to Chargaff's law. So always remember:
A pairs with T (Adenine with Thymine)
C pairs with G (Cytosine with Guanine)
Whenever you need to figure out the other strand, just switch the original base sequence with their base pairs to get the second strand/sequence.
Hope this helps you for future questions. Have a good day, love <3