multipart question. thanks for help.

1. ABC extends credit to its customers on terms of 1/10, net 40. Assuming a customer pays the invoice at the end of the costly trade credit period, what is the annualized cost of trade credit? (Show your answer in decimal form to four places, e.g., 12.34% would be 0.1234)

2. You borrowed $84,000 from a loan shark. He charges an annual interest rate of 22.1 percent but requires you to make weekly payments and pay the loan off in full within one year. given these terms, how much is each weekly payment? Show your answer to the nearest dollar.

3. Although Bill has nothing saved for retirement so far, he has determined that he will need to have $813,000 in the account when he retires. He plans to open a retirement account and make monthly contributions from his paycheck. The account that earns 8.4 percent annual interest (which is compounded monthly). How much will he have to invest each month to be able to reach his goal at the end of 26 years? Show your answer as a positive number to the nearest penny.