Solve for "k": 15k - 9 + 44 = 110

The line containing the midpoints of the legs of right triangle abc where a(-5,5), b(1, 1), and c(3, 4) are the vertices.

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?

This is so hard and it’s for a test