John Smith, a plumber, entered into a yearly agreement with a chain of restaurants to perform all plumbing repair services. The yearly agreement provides for the payment by the chain of restaurants to John Smith of a fixed fee of $18,000 on January 1 of each year plus amounts for parts and materials billed separately by John Smith at the end of each month. Ampunts billed at the end of one month are collected at some point in the future. During the first two months of 2020 , John Smith makes the following billings, cash collections and cash pavments. Required: 1) Calculate the amount of cash-basis income for tahen e._.tol a 29. muat accountng principle is used to determine revenue under the accrual basis? ( 1 mark) 4) What accounting principleconcept is used to determine cepenses under the accrual basis? ( 1 mark)