In many contracts there are more promises than one on a side. If each promise on one side is supported by a promise or performance allotted to it exclusively as its consideration, the contract is divisible.53 But frequently all promises or performances on one side are indiscriminately made consideration for all promises or performances on the other. And if the performances or promises on one side fulfil the legal requirements of consideration they will support any number of counter-promises on the other.54 A common illustration some specific quantity, though it is clear that the performance of such a promise involves detriment in refraining from dealing with any other person than the promise. See supra, Sec. 104.

50See supra, Sec. 115.

51 See supra, Sec. 44.

52 See infra, Sec.Sec. 794 et eeq., and especially Boston Store v. Schleuter, 88 Ark. 213, 114 S. W. 242; Young p. Stein, 152 Mich. 310, 116 N. W. 195, 17 L. R. A. (N. S.) 231, 125 Am. St. 412, Elliott Contracting Co. v. Portland, 88 Oreg. 150, 171 Pac. 760.

53 See infra, Sec. 861.

54 Franklin Telegraph Co. v. Harrison, 145 U. S. 459, 36 L. Ed. 776, 12 S. Ct. 900; Philadelphia Ball Club v. Lajoie, 202 Pa. 210, 51 Atl. 973, 58 L. R. A. 227, 90 Am. St. Rep. 627. Sbrta v. Ontonagon Valley Land Co., 148 Wis. 186.134N.W. 341. In Pfeiffer v. Adler, 37 N. Y. 164, it was held that an oral promise to sell goods to a responsible person on the usual terms, would not support an independent engagement to pay the antecedent debt of a third person. See also Luing v. Peterson, (Minn. 1919), 172 N. W. 692; and in Belknap v. Bender, 75 N. Y. 446, 31 Am. Rep. 476, it was held that a promise to work at what appeared to be full compensation would not support a promise to pay such a debt. In both of the New York cases the primary question was whether the promise was to answer for the debt of another and, therefore, within the Statute of Frauds; but in so far as they hold that aside from the necessity of a writing, the agreements were invalid because the consideration was insufficient, they are indefensible. (A contrary decision is Davies v. Carey, 72 Wash. 537, 130 of this principle is found in a sale with a warranty. The consideration for the promise to warrant is the making of the sale for the agreed price.55 A promise to a buyer in consideration of his agreement to buy, that the seller will on a certain contingency repurchase is also valid,56 or that he will repay a commission on a certain contingency.57 Another common illustration is where a business is sold for an agreed price paid, or promised, and the seller further promises not to engage in competition with the buyer. This promise is supported by sufficient consideration.57a In this connection may also be considered a lease, in which is included an option to the lessee.58