Question

Why was Antonio unable to lend Bassanio the money that he needed? How did he propose to help his friend?

Answer 1

Antonio was unable to lend Bassanio the money that he needed because all his fortunes were at sea. At the moment he did not have the money or commodity to give Bassanio the amount requested.
He told Bassanio to go to Venice and take a loan on behalf of Antonio from the wealthy merchants there.