SAT1000 - P866

Algebra Level 3

For all real numbers $x$ and $y$ , which of the following options is always true?

$A.\ \lfloor -x \rfloor=-\lfloor x \rfloor$

$B.\ \lfloor 2x \rfloor=2\lfloor x \rfloor$

$C.\ \lfloor x+y \rfloor \leq \lfloor x \rfloor + \lfloor y \rfloor$

$D.\ \lfloor x-y \rfloor \leq \lfloor x \rfloor - \lfloor y \rfloor$

Have a look at my problem set: SAT 1000 problems