Bob is a buyer and a seller. He makes money buying things and selling them at a profit. He sells items online and at pop up markets. He buys and sells many types of items but his specialty is old furniture.

Bob hires Mary to be his agent. Marys agency duties include traveling around Maryland and buying old furniture for Bob. Mary is somewhat of an expert on the matter of old furniture. Mary has the authority to spend up to $10,000 for furniture she purchases for Bob.

One day, Mary is at an antique shop. She finds two pieces of furniture that she knows Bob would like, a chair and a side table. The seller wants $3,000 for the chair and $11,000 for the side table. Mary thinks the chair is worth a lot more than $3,000. She thinks its worth at least $5,000. She also believes the side table is worth at least $12,000.

Mary buys the chair with her own money for $3,000. She later sells the chair online to a woman in Florida making a profit of $2,000.

What duties has Mary breached? Explain fully. Also, use only the facts above. Do not assume anything. All the facts are in the question.