How do i find the entire term containing x^51 in ((x^6/2)-(2/x))^12

the powers of x go like this

6*12-0, 6*11-1, 6*10-2, 6*9-3, ...
= 72, 65, 58, 51, ...

So, the 4th term is

12C3 (x^6)^9 (1/x)^3 = 220x^51