Can you guys tell me the answer i'm stuck

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 of the following is the true for f(x) = 5cos

What are the solutions of the system? solve by graphing. y = x^2 + 3x + 2 y = 2x + 2