To visualize better, look at it like this:
![(3r^3)/(2r)](https://img.qammunity.org/2019/formulas/mathematics/middle-school/hztdx8vvf0oofcjx1g9iu24ye6sdpe2kvj.png)
First, see if you can simplify 3/2. You can't, so leave it like that.
The rule for exponents is you subtract the exponent from the bottom (r) from the exponent on the top (
)
![r^3 - r^1 = r^2](https://img.qammunity.org/2019/formulas/mathematics/middle-school/cu2hqv8itkbveqc7idckbsmzjs8q5a1okz.png)
Put that on the top, and you get
![(3r^2)/(2)](https://img.qammunity.org/2019/formulas/mathematics/middle-school/ukz7i734e77g45itkz7ebt7whtwvtqwqtd.png)