Question 21
The graph of $2x^2 + xy + 3y^2$ $- 11x - 20y + 40 = 0$ is an ellipse in the first quadrant of the $xy$-plane. Let $a$ and $b$ be the maximum and minimum values of $\dfrac{y}{x}$ over all points $(x, y)$ on the ellipse. What is the value of $a + b?$