Answer:
13 
Step-by-step explanation:

x=40/3 = 13 
I can help you what do you need
For this case we have that by definition, the discriminant of a quadratic expression is given by:

If the discriminant is less than zero then the expression has two different complex roots.
In this case we have the following expression:

So we have to:

The discriminant is given by:

Then, if we want two complex roots it must be fulfilled that:

Thus, the expression has two complex roots for all values greater than 4.
ANswer:

B. and D. work. You are trying to figure out how many more cars they painted in the first and second years together than the third year. (5,000+7,213)-8,201=4,012