There is no meaningful way of doing so.
x + y = 3 is a linear equation in two variables
x2 + x = 3 is a quadratic equation in one variable.
Both have the same number of terms but they are not of the same kind.
classifacation of algebraic expression according to the number of terms
a common factor
2n
The Base in the Algebraic Expression can be a Number or A Variable. EX. 42 or X2 - 4 and X are the base.
an algebraic expression is an expression built up from constants, variables, and a finite number of algebraic operations (addition, subtraction, multiplication,division and exponentiation to a power that is a rational number). For example,
Let the number be x and so the expression is 8x
If you call your number x, the expression would be 5x.
The algebraic expression for three more than a number is: X + 3
37n
4x
2b
16n