Explanation:
Expression are problems with operations and terms, but no equal sign(s).
Note: If a problem has an equal sign, it's an equation.
*By eliminating the problems with equal signs, 12/4 =3 and 12 = 4 x 3 are incorrect.
12 + 4 - 3 and 12 - 4(3) are expressions, due to both problems not having an equal sign.