9. installment sales for 2018 is $600,000 and cost of goods sold $300,000 while the installment sales in 2019 is $1,000,000 and cost of goods sold $800,000, cash collection from 2018 sales was $400,000 in 2018 and $200,000 in 2019, cash collection from 2019 sales was $500,000 in 2019 and $500,000 in 2020, using installment sales method compute gross profit rate for two years sales?

a. 2018 is 50% and 2019 is 50%.

b. 2018 is 50% and 2019 is 20%.

c. 2018 is 20% and 2019 is 50%.

d. 2018 is 20% and2019 is 20%.