Well i know that 12x12=144 so it is 12!
Given:
The given equation is

To find:
All the real solutions.
Solution:
We have,

It can be written as


Using zero product property, we get
and 
and 
and 
We know that
is an imaginary number because there is a negative sign under the square root.
Therefore,
is the only real solution of the given equation.
0.10(5000) = 500
0.15(10,000) = 1500
total commission on 15,000 = (150 + 500) = 2,000