Answer:
[tex]r=\dfrac{I}{Pt}[/tex]
Step-by-step explanation:
Solve this the way you do any "solve for" problem. Locate the variable of interest and identify what has been done to it. Undo that.
Here, the variable of interest is "r". It has been multiplied by Pt. We undo that multiplication by dividing by that product:
[tex]I=Prt\\\\\dfrac{I}{Pt}=\dfrac{Prt}{Pt}\\\\\dfrac{I}{Pt}=r \quad\text{simplify}[/tex]
