The absolute value 
returns the "positive version" of a number.
In other words, if the number is positive, it remains positive; if the number is negative, it changes sign.
So, if we want 
, we want the "positive version" of x to be 9.
This can happen in two ways: if x is already 9, then its absolute value is still nine. If instead x=-9, its positive value will be 9 again.
In formula, we have
because
Y=12.5x
because 12.5 is the constant and this is a directly proportional equation
Remark
I don't know exactly what level you are in, but the obvious factors are
y = 2x*(x^3 + 11x + 30)
This gives one more factor somewhere around x = -11.3 . Notice that the minimum is around - 3000 or so. I don't think anyone is going to try and take this any further. My calculator figures out cubics and gives an answer of -11.23. There are two other roots but they are a complex pair.
Answer
factor 1: 2x
factor 2: x^3 + 11x^2 + 30
