Yolanda agrees to bathe and groom Wendy's dog, Fluffy Puff, for $30. Yolanda agreed to the price before seeing Fluffy Puff who is a chubby dog with lots of hair. Yolanda tells Wendy that if she is going to groom Fluffy Puff, the price will be $40. Wendy reluctantly agrees but tells Yolanda that she should not have been surprised that a dog named Fluffy Puff had lots of hair. Yolanda bathes and grooms Fluffy Puff, but Wendy will only pay $30. Which of the following is correct regarding Yolanda's entitlement to the extra $10?