We have a number: a*10^3 + b*10^2 + c*10 + d

If we add: c*10 + d, we get:

a*10^3 + b*10^2 + 2c*10 + 2d

If we subract: a*10 + b, we get:

a*10^3 + b*10^2 + (2c - a)*10 + (2d - b) = 5689

b >= 1 --> a = 5

b - 1 = 6 --> b = 7

2d + 10 - b = 9 --> d = 3

2c + 10 - a - 1 = 8 --> c = 2

10c + d = 23