Final answer:
Consideration is a key element in contract law. Mike's installation of a doggie door could be considered consideration for Betty's promise to give him a puppy. Whether Mike can enforce Betty's promise depends on the legal concept of promissory estoppel.
Step-by-step explanation:
Consideration is a key element in contract law and refers to something of value given by each party to a contract. In this case, Mike's installation of a doggie door could be considered consideration for Betty's promise to give him a puppy, as it involves a change in Mike's living arrangements.
However, whether Mike can enforce Betty's promise depends on the legal concept of promissory estoppel. Promissory estoppel allows a party to enforce a promise even without consideration, if they have reasonably relied on the promise to their detriment. In this case, if Mike can show that he relied on Betty's promise and suffered a significant detriment by installing the doggie door, he may be able to enforce her promise.
It is important to consult with a legal professional to fully understand and apply contract law in specific situations.