Help please I really need to pass this class

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

Find x to the nearest hundredth place

International calls require the use of a country code. many country codes a 3-digit numbers. country codes do not begin with a 0 or 1. there are no restrictions on the second and third digits. how many different 3-digit country codes are possible?