For this case we have the following equation:

Rewriting we have:

Dividing by 2 to both sides of the equation:

We apply the quadratic formula:

We have to:

Substituting:

Thus, we have two roots:

ANswer:

It equals 5/6. If you want to know why, just ask me.
FOIL
x^2+11x-9x-99
x^2+2x-99
I am thinking that c is correct and i am truely sorry if u get it wrong