Answer
$\frac{r^{3}}{t^{12}}$
Work Step by Step
$\frac{r^{3}t^{-7}}{t^{5}}$
First, move t$^{-7}$ to the denominator (the -7 indicates that this variable should be moved to the opposite side of the fraction line):
$\frac{r^{3}}{t^{5}t^{7}}$
Now, as the two variables in the denominator are the same variable, add their exponents:
$\frac{r^{3}}{t^{5+7}}$ = $\frac{r^{3}}{t^{12}}$
