Answer:
b = -a
Step-by-step explanation:
If a and b are both positions from 0, we need to write an equation that relates both positions. The problem is explaining that the position of a is opposite to the position of b.
If a = 2; b = -2. If a = 1000; b = -1000.
If a = -x; b = x. Then:
-a = x
-a = x and b = x, that means:
b = -a