Question 302566
{{{(2s^-1t^3/6s^2t^-4)^-3}}}

any negative power can be written as : s^-1{{{(1/s^1)}}}

Therefore: 

{{{((2t^3t^4)/(6s^2(s)))}}}^-3 

{{{(2t^7/6s^3)}}}^-3

{{{(t^7/3s^3)}}}^-3

{{{(3s^3/t^7)}}}^3

{{{(27(s^9))/(t^21))}}}