Hello Hannah,
Is there a drawing with the problem, from which I can assume <B is the same as saying <CBA,
and <D is the same as angle <CDA?
If that is true, here is the proof:
S1) <DCA ≅ <BCA R1) Given
S2) <B ≅ <D R2) Given
S3) Seg(AC) ≅ Seg(AC) R3) Reflexive Property
S4) ΔCDA ≅ ΔCBA R4) AAS
S5) Seg(AB) ≅Seg(AD) R5) CPCTC
Thank you for the question, and have a great evening!
Michael Ehlers