Variable -A letter that represents an unknown number.
Expression -Any single number or variable, or combination of operations... (-, +, x, /) involving numbers and variables.
e.g. 5, n, 8t, x+1, 2y, -7
1+1=2 -Equation not expression
Value - A known or calculated amount
Constant -A number that does not change and it increases or decreases the value of the expression
Numerical Coefficient -A number that multiples the variable (or a number in front of a variable)
(2 being the numerical coefficent and 't' being the variable)