I like the example the other person gave:
5 + (-5) = 0
And from your comments:
a) write an equation with three numbers that add up to 0.
6 + (-2) + (-4) = 0
b) write a different equation with four numbers that add up to 0,without using opposites like you can’t use -30 and 30
10 + 2 + (-4) + (-8) = 0
c) write an equation using four numbers that multiply to 0, without using opposites
6 x (-3) x (-2) x 0 = 0