1) A contingent contract is one where performance depends on an uncertain future event outside the parties' control. Contingent contracts can only be enforced after the event occurs. If the event becomes impossible, the contract is void.
2) For contracts contingent on a specified event happening within a fixed time, if the event does not occur by the expiration of the time, the contract becomes void.
3) A valid tender of performance must be unconditional, made at the proper time and place, and allow the promisee to reasonably ascertain that performance will be rendered.
4) For joint promises, any joint promisor can be compelled to fully perform unless otherwise agreed. A release of one joint promisor