## Thinking Mathematically (6th Edition)

Translation to algebraic expression (not simplified yet): $x - (x+4)$ Simplified form: $-4$
Let $x$ = the unknown number Then sum of the number and four = $x + 4$ A number decreased by the sum of the number and four = $x - (x+4)$ Simplifying gives: $=x-x -4 \\=-4$