Verified Answer :

3 = coefficient
x = variable
3x = term
5 = constant
3x + 5 = expression
3x + 5 = 20 = equation.

Ok so first lets write the equation:-

3x + 5 = 20

A coefficient is the number before any variable. So 3 is the coefficient. 
A variable is a letter which stands for a number. So x is the variable
A term is a coefficient and variable together. So 3x is the term.
A constant is a number on its own. So 5 is the constant. 
A expression is  a mathematical phrase. So, 3x + 5 is the expression. 
A equation is a way to show that 2 things are equal in math. So 3x + 5 = 20 is the equation. 

So, 

Coefficient = 3
Variable = x
Term = 3x 
Constant = 5 
Expression = 3x + 5 
Equation = 3x + 5 = 20

Hope I helped ya!! xD