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.
Both use numbers and variables; however it is all based on the arrangement. So let's take look at both to determine their use and relationship. An expression is a combination of numbers, variables, and symbols to be calculated. An equation contains expressions that are separated by an equals sign. A further look at the mathematical expression can be explained with numbers and variables such as: 7x + y - 4.