Answer :

[tex]\dfrac{3p}5=12\\3p=12\cdot5\\p=\frac{12}3\cdot5\\p=4\cdot5\\p=20[/tex]
[tex]\frac{3p}{5}=12\ \ \ \ |multipy\ both\ sides\ by\ 5\\\\\not5^1\cdot\frac{3p}{\not5_1}=5\cdot12\\\\3p=60\ \ \ \ |divide\ both\ sides\ by\ 3\\\\\frac{3p}{3}=\frac{60}{3}\\\\\boxed{\boxed{p=20}}[/tex]