6. (6 points) Small Company rendered services to customers amounting to $10,000 during 2020; the related cash was collected as follows: $1,000 in 2019, $6,000 in 2020; $3,000 in 2021. During 2020, $8,000 of expense was incurred; the related cash payments were made as follows: $500 in 2019; $6,000 in 2020; and $1,500 in 2021. Based only on these data, provide the following amounts: Total revenue for 2019 Total revenue for 2020 Total expense for 2019 Total expense for 2020