In this chapter, unless a contrary intention appears—
(a) a reference to the amount of money payable under a contract is taken to include all amounts that, under the contract, contribute to a complete or partial satisfaction of the contract price; and
(b) a reference to the payment of any money in reduction of the contract price for a contract includes all amounts that, under the contract, contribute to a complete or partial satisfaction of the contract price; and
(c) a reference to completion of the work specified in a subcontract is taken to be completion of the work by a subcontractor who has given a notice of claim in relation to the contract, subcontract or a higher subcontract.