why is willy constanly yelling at linda ? how does biff react to this ?

Willy constantly yells at Linda because she interrupts him, because she mends her stockings instead of purchasing new ones (she's thrifty, and he won't admit she needs to be). Biff gets angry when Willy yells at his mother, particularly about the stockings. He knows that Willy promised the woman in the hotel room a pair of stockings and accused Biff of giving her the stockings that should have been his mother's.