Help please stuck! Maths

[LLLTB]

Three numbers multiplied together give an answer of -12
The sum of Two of the number is zero

What could the three numbers be?

My brother is stuck help

Well if the sum of two of them is 0 then two are the same, with one being a minus (-20 and +20 for example). Use that to work out the combinations that work - there are several.

2,-2 and 3 make -12

As DishedUp says, or 12, 1, -1

-3, -1 and 4?

Sorry, I thought it was the sum of all 3, just read too quickly

Depending on his age, the set of possible answers may go beyond whole numbers, e.g. 0.5, -0.5 and 11.75. (Same pattern can also apply using fractions and square roots, but not so easy to type here.)