'Like Terms"

Like terms are when you can combine an expression having the same variables and exponent.
100p and 3000p are like terms because they have the same variables. Yes we can combine them.
P and p^2 are not like terms because they both do not have exponents. We can not combine 2d+2f because they don't have the same variables. An expression cannot have an equal sign because ten it will not be an expression. It will be an equation.

Perimeter- Perimeter is the surrounding of a polygon.