What is Biff's business plan? Why does Willy need Biff's plan to work? What is Biff willing to sacrifice to help his father?

For the first time since the play's beginning, everything appears to be coming together for Willy during Scene 11. Although the scene opens with an argument between Willy and Biff, the scene shifts as Biff attempts to reconcile with his father. Up until this point, Willy has relied upon favorite memories — memories in which Biff adores him — rather than accept the disintegrating relationship with his oldest son. Willy feels he has finally achieved a position of authority and respect again. As a result, he immediately begins to dictate what Biff should do when he visits Oliver.

The problem is that Biff wants to be honest with Willy, but Willy will not give him the chance. Each time Biff makes a statement, Willy interrupts him and interprets the partial statement as he wants it to be. Thus, Willy believes Oliver is already funding Biff, while Biff desperately tries to tell him he has not even seen Oliver yet. As the discussion continues, Biff, Happy, and Linda exaggerate facts, add details, and adopt confident attitudes in order to maintain Willy's fantasy.

Tension arises when Biff and Willy begin to argue over Linda. Even though Linda is determined and vocal within Scene 10, she remains submissive in Willy's presence. Biff resents how Willy treats Linda for two reasons. First, he despises the fact that Willy degrades his mother and insults her, especially when she is merely trying to encourage Willy and the boys. Second, Biff is incapable of forgiving Willy for his affair. As far as Biff is concerned, Willy betrayed his mother, even if the Woman meant "nothing" to him. As a result, Biff assumes a protective air around Linda, and he will defend her against anyone, even his father.

Explanation:

she was trying to use   reliable narrator.

i think that will have something to do with the mississippi river but google will know the full answer for sure