Answer:
9/16
Step-by-step explanation:
Smooth coat (S) is dominant over rough coat (s) and black coat (B) is dominant over white coat (b).
SsBb x SsBb
Offspring (You can also see the attached image for the Punnet's square analysis)
9 S_B_ = Smooth black coat
3 S_bb = smooth white coat
3 ssB_ = rough black coat
1 ssbb = rough white coat
Hence, on average, 9/16 of the offspring will have a smooth black coat