Given any positive even integer, x, the positive difference between the smallest odd number greater than 9x - 2 and the largest odd number less than 8x + 3 can be written in the form ax + b. What is a + b?

a + b = 21.

If x is a positive even integer then so is 9x -2, so the smallest odd number greater than this must be 9x-2+1 = 9x-1

Similarly, 8x+3 must be an odd number, so the largets odd number less than this must be 8x+3-2 = 8x + 1

Can you finish from here?