What is the image of (7,8)(7,8) after a reflection over the line y=xy=x?

Based on what i know about mean, this doesn't add up.

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 inequality comparing two of the expressions is true when 0.7 < x < 0.9