The set given is {1, 3, 5, 7, 9, 11, 13} and is asked in the problem to determine the number of integers that are defined as the difference of the two numbers.
differences:
2, 4, 6, 8, 10, 12
2, 4, 5, 8, 10
2, 4, 6, 8
2, 4. 6
2, 4
2
Hence the solution set is {2, 4, 6, 8, 10, 12}. The answer is 6 integers.