Answer:
-x = 0
Step-by-step explanation:
-x = 0 because it has only one variable (x), and the rest all have at least two variables.
hope this helps :)
5x-20
since it says "product of 5 and x" we know that 5 and x is being multiplied
5x
since it says 20 less than we know that we need to subtract 20 from 5x
3x-4=-8
3x=-8+4
3x=-4
x=-(4/3)
-7(1/7) = -1
since it is exactly in the halfway between 
