4. Zenia contracts with Yvonne for a supply of specialized computer components worth $6,000, which she needs to meet a contract to supply Wendy with 60 laptop computers, a contract which is worth $65,000 to Zenia. Zenia makes it clear to Yvonne that her contract with Wendy is vital to let her get established in the market and that it is imperative that Yvonne meet the deadline. "If you can't," she says, "I'll take the business to someone who can." Yvonne wants the business badly, so, against her better judgment, she agrees to a clause in the contract which says that, for every day delivery is late, she will pay Zenia $10,000. What type of clause is in the contract and is it enforceable