If f(x)f(x) is an exponential function where f(3.5)=10f(3.5)=10 and f(9.5)=30f(9.5)=30, then find the value of f(12)f(12), to the nearest hundredth.

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?

Which one ? is the answer and how to find this answer

Find the value of x for which line a is parallel to line b