What is the the a coefficient and a variable

Charlie is a car salesman he earns $800 plus a 9% commission on all of her sales for the week if charlie receive the payment for $1960 this week how much where is total sales

For what type of equity loan are you lent a lump sum, which is to be paid within a certain period of time? a. a line of credit b. equity c. a second mortgage d. an amortization

What is r i 4.5+10r=-6.5 with work pls