Yin Han is the business representative of Yuanda Trading Company, and holds a blank contract stamped with the official seal of the company. His behavior of signing a contract with Kerry Garment Factory constitutes an agency by estoppel, and the signed contract is valid. Yuanda Trading Company shall pay the purchase price according to the contract and bear the liability for breach of contract. The losses caused by Han's signing a contract with Yuanda Trading Company beyond the authorized scope shall be recovered by Yuanda Trading Company.