“They replied.
‘We are able.’”
οἱ δὲ εἶπαν αὐτῷ Δυνάμεθα.
There is something similar to this in Matthew, chapter 20:22, almost word for word. Mark said that the 2 sons of Zebedee, James and John, responded to Jesus (οἱ δὲ εἶπαν αὐτῷ) that they were able (Δυνάμεθα) to drink from the cup and be baptized with the suffering. Of course, the brothers said that they would be able to undergo the suffering cup and this difficult baptism. They thought very highly of themselves, since they were among the elite disciples and apostles of Jesus.