Agent Authority And Third Party Knowledge

Martha hires Janet as a sales representative, explicitly instructing her that any sale exceeding $10,000 or including a discount greater than 8 percent requires Martha's express approval. Janet subsequently signs a contract with a long-standing customer who is aware of these limitations on Janet's authority. The contract is for $25,000 worth of goods and includes an 11 percent discount. If Janet did not obtain Martha's approval prior to signing, which of the following statements regarding the contract is true?