i have the equation $\displaystyle \mid x - 1 \mid = 1 - x$

i opened up the modulus to get $\displaystyle x - 1 = 1 - x$ & $\displaystyle 1 - x = 1 - x$

and the answer is supposed to be the inequality $\displaystyle x \le 1$ but ive no clue how to get to this.