Is it possible for a number to be a rational number that us not an integer but is a whole number?

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

What is the value of x in the following equation. -x ^3/2 = -27

Tim's phone service charges $26.39 plus an additional $0.21 for each text message sent per month. if tim's phone bill was $31.64, which equation could be used to find how many text messages, x, tim sent last month?