Answer: [tex]\displaystyle r = \frac{e^2}{p}[/tex]
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Work Shown:
[tex]p = \frac{e^2}{r}\\\\pr = e^2\\\\r = \frac{e^2}{p}\\\\[/tex]
Explanation:
In the second step, I multiplied both sides by r to move it to the left side. Then I divided both sides by p to isolate r.
In short, the r and p swap places.
