Need help with college math

Question

by air the distanice from city A to city B is 3003 miles less than the distance from city C to city D if the total of these two distances is 7867 miles find the distance from city C to city D

Answer 1

Let x = the distance from city C to city D

Let x-3003 = the distance from city A to city B

x + x -3003 = 7867

2x -3003 = 7867

2x = 10,870

  x = 5435 miles