A sum of Rs. 46,800 is divided among A, B, C and D in such a way that the ratio of the combined share of A and D to the combined share of B and C is 8 : 5. The ratio of the share of B to that of C is 5 : 4. A receives Rs. 18,400. If x is the difference between the share of A and B and y is the difference between the share of C and D, then what is the value of (x - y) (in Rs.)?