Equity will give rescission for a mutual mistake of the parties to a deed concerning the extent of grantor's undivided interest in the land conveyed,1 or for a mistake as to the extent of an estate in realty as to its duration.2 If A sells his interest in land to B, both parties thinking that A has a remainder in property which the life tenant has the power to sell if necessary for her support, when in fact the life tenant has already died, such mistake avoids the contract.3