5. Show that f(x) = 5x- 6 and f-1(x) = x+6/5 are inverse functions using composition of functions

Dakota earned $7.50 in interest in account a and $18.75 in interest in account b after 15 months. if the simple interest rate is 4% for account a and 5% for account b, which account has the greater principal? explain. to make it a little easier, there is an image. good luck!