Question

Negative three times a number is at least 57.

Answer 1

The option formatting isn't very clear, anyway: given a number x, negative 3 times that number is -3x. If this has to be at least 57, it means that -3x must be greater than or equal to 57:

$-3x\geq 57$

Dividing both sides by -3 solves the equation, but we have to switch the inequality sign because we're dividing by a negative number:

$x\leq \dfrac{57}{3}=19$