What do i do on this both top and bottom

If f(x)= 3x+6 which of the following is the inverse of f(x)

Use the frequency distribution, which shows the number of american voters (in millions) according to age, to find the probability that a voter chosen at random is in the 18 to 20 years old age range. ages frequency 18 to 20 5.9 21 to 24 7.7 25 to 34 20.4 35 to 44 25.1 45 to 64 54.4 65 and over 27.7 the probability that a voter chosen at random is in the 18 to 20 years old age range is nothing. (round to three decimal places as needed.)

Jacks bank statement shows an account balance of -$25.50. which describes the magnitude, of size, of the debt in dollars