Answer:
[tex]x^{3r-18}[/tex]
Step-by-step explanation:
[tex]\frac{1}{x^{18-2r} } x^{r} =\frac{x^{r} }{x^{18-2r} }[/tex]
[tex]=x^{r-(18-2r)} =x^{r-18+2r}[/tex]
[tex]=x^{3r-18}[/tex]
Hope this helps
