She looked at him curiously - at his ugly tweed suit, his yellow boots, and up into the strong, forceful face with eyes set in deep hollows under his protruding brows, at the heavy jaws giving a certain coarseness to his expression, which his mouth and forehead, well-shaped though they were, could not altogether dispel.
Definition of Expression. An Expression is a mathematical phrase that combines numbers and/or variables using mathematical operations. An expression is a representation of a value; for example, variables and/or numerals that appear alone or in combination with operators are expressions.
An equation is a mathematical statement that two expressions are equal. In a simple numerical equation, expressions made of numbers and operations appear on each side of an equals sign. The equals sign means that the two expressions have the same value. For example, 3 + 9 = 12 is an equation.