The formula for the future value v (in dollars) of an investment earning simple interest is v=p+prt, where p (in dollars) is the principal, r is the annual interest rate (in decimal form) and tt is the time (in years).

a. solve the formula for p.

p=

b. an investment earns 8% simple interest. what amount of principal is needed to have $6000 after 7 years? round your answer to the nearest cent.

amount of principal: $