Question 154319
Simplify and write with positive exponents 9x ( x^-3) / 18 x^15.
: 
Use the reciprocal to get rid of the neg exponent:
{{{(9x)/x^3}}} / {{{(18x^15)}}}
Same as:
{{{(9x)/x^3}}} * {{{1/(18x^15)}}}
:
Cancel 9x into 18x^15, multiply denominators:
{{{1/x^3}}} * {{{1/(2x^14)}}} = {{{1/(2x^17)}}}