Answer:
It is.
Explanation:
It is.
I had this same problem when I was younger so I'm going to explain it to you how I would've liked it to be explained to me.
2p+4p=6p. Why? Because if two things are multiplied by the same thing (for example, 49 * 5 + 51*5), you can do 100 * 5 instead of doing it out. So any time you see a variable without a co-efficient which is the number before the variable, think of it as 1p instead of p, so it would be 1p+4p which does equal 5p. Since multiplying anything by 1 is just the identity property, it doesn't change the value of p but it becomes a little easier to visualize. As you practice this more, it'll get more familiar and you won't have to remember it like this anymore.
Hope this helped, tell me if you have any questions.