25B [Definition of fundamental breach: substantial deprivation of expectation, etc.];

49A1 [Buyer's right to avoid contract (grounds for avoidance): fundamental breach of contract];

74A [General rules for measuring damages: loss suffered as consequence of breach];

81C [Effect of avoidance on obligations: return of defective goods];

84A [Restitution of benefits received: seller bound to refund price must pay interest]