15PTS PLEASE HELP ASAP!
(dont write random answers pls)

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?

What is the equation of a vertical line passing through the point (−5, −1)? y = −5 y = −1 x = −5 x = −1

Find the solution of this system of equation -7x+y=-20 9x-3y=36