Write the English phrase as an algebraic expression. Then simplify the expression. Let $x$ represent the number. A number decreased by the sum of the number and one. What is the algebraic expression? (Do not simplify.)

Step 1 ：Translate the English phrase into an algebraic expression. Let $x$ represent the number. The phrase 'A number decreased by the sum of the number and one' translates to $x - (x + 1)$

Step 2 ：Simplify the algebraic expression using Python code. The simplified expression is $-1$