assuming r is another variable (and not a typo), here is how to solve that.
[tex]rp-6=2p+20[/tex]
[tex]rp-2p=26[/tex]
[tex]p(r-2)=26[/tex]
[tex]p= \frac{26}{r-2} [/tex]
so the value of p is [tex]p= \frac{26}{r-2} [/tex]
Now, if r was a typo, we can substitue 1 in for r giving us
[tex]p= -26[/tex]
