Question 192920
restating  the  problem  as we  understand  it

(x^3 *y^(-4))/ ( (5x)^6 * y^(-8))

we  usually  look  at  coefficients,  x's  ,  and  y,  separately

coefficients,  1/(5^6)=1/15625

x's,  x^3/x^6=x^-3=1/x^3,  remember  to  divide  common  bases  subtract exponents, and a  negative  exponent  indicates  a  reciprocal.

y's,  y^(-4)/y^(-8)=  y^( (-4)-(-8))=y^4

combining  y^4/((15625)*(x^3))

to  check  let  x=2,y=3  arbitrarily

answer  is  3^4 /(15625*(2^3))=81/(15625*8)=.000648

original  is  ( 2^3*3^(-4)0/((5*2)^6 *3^(-8))=8(.0123)/(1000000*.0001524)=.0984/152.42=.000645 ok