17=3(p-5)+8
You have 2 choices, and I will show you both ways of solving this. I would do it like this:
17=3(p-5)+8 Subtract the 8 over to the other side
9=3(p-5) Divide both sides by 3
3=p-5 Add 5 over to the other side
8=p
The other way (which is sometimes better with certain numbers, but not in this case):
17=3(p-5)+8 Use the distributive property to multiply the 3 by each term in parentheses,
17=3p-15+8 Combine like terms
17=3p-7 Add 7 over to the other side
24=3p
8=p
In this case, that was probably more work.