Answer:
Use the value for the variable to solve for the other unknowns. Substitute the value for the variable into the expression for the number of seats on the middle level. Substitute the value for the variable into the expression for the number of seats on the lower level.
I think it's 0 since anything multiplied by 0 is, well, 0! No matter what the sign is. I believe the correct answer is 0 :)
X = 42
x/3 - 4 = 10
+ 4 +4
x/3 = 14
•3 •3
x = 42
If your original equation was 
, then a reflection over the x-axis means you need all the y-values to switch sign. This means you need to multiply that function by -1.
or 
