In case where A makes a promise to B, the consideration may (a) consist of a legal right which B gives up to A, and which A acquires from B. This is the most usual and natural form of consideration and is, of course, sufficient.1 A promise by a remainderman to pay a debt of the life tenant is sufficient consideration for a promise by the life tenant to pay interest to the remainder-man.2 A loan by A to B is consideration for B's promise to assume X's debt to A.3