Question

Billy thinks of a number that is not zero.

Answer 1

The answer could be negative or positive. We are not given specific as to whether or not the starting number is positive or negative so therefore it could be either.
Hope this is helpful :)

Answer 2

SOLVING

$\Large\maltese\underline{\textsf{A. What is Asked}}$

Billy thinks of a nonzero number. He multiplies it by 3. He gets...? 3 options given

$\Large\maltese\underline{\textsf{This problem has been solved!}}$

This problem does not give us the information about the starting number (we can't read Billy's mind).

First, I'm going to assume that the number is positive

$\bf{A\;positive\;number\;multiplied\;by\;-3;\;yields\;a\;negative}$

Next, I'll assume that Billy's number is a negative one.

$\bf{The\;number\;is\;a\;positive\;one}$.

$\rule{300}{1.7}$

$\bf{Result:}$

              $\bf{=The\;answer\;could\;be\;either\;positive\;or\;negative.\;It\;depends\;on\;the\;sign}\\of\:the\:starting\:number.$