Answer:
CTAATGT i believe.
Explanation:
A=T
C=G
G=C
T=A
If you replace GATTACA with these complementary parts/letters, etc. you will get your answer!
Hope this helps!
Tip: The only thing that changes when finding an RNA strand is that there is Uracil (U). So when finding a complementary RNA strand A=U while everything else is the same.
