Question

all real numbers at most –3.5 or at least 7.5

Answer 1

The set of real numbers that are at most -3.5 or at least 7.5 can be represented as:
{x | x ≤ -3.5} ∪ {x | x ≥ 7.5}

This set includes all real numbers less than or equal to -3.5 and all real numbers greater than or equal to 7.5.