The product of the roots of the quadratic equation $2 x^{2}+p x-p+4=0$ is 9 . What is the sum of the roots of this equation?
The product of the roots of the quadratic equation $a x^{2}+b x+c=0$ is $\frac{c}{a}$ and the sum of the roots is $-\frac{b}{a}$.

Since the product of the roots of $2 x^{2}+p x-p+4=0$ is 9 , then $\frac{-p+4}{2}=9$ and so $-p+4=18$, which gives $p=-14$.

Therefore, the quadratic equation is $2 x^{2}-14 x+18=0$ and the sum of its roots is $-\frac{(-14)}{2}=7$. ANSWER: 7