#### Answer

Translation to algebraic expression (not simplified yet):
$x - (x+4)$
Simplified form:
$-4$

#### Work Step by Step

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:
$=x-x -4
\\=-4$