Problem of the Day – November 22, 2019

Line $A$ is defined by $y = 4x + 3$ and line $B$ is defined by $y = 4$, and they intersect at a point, $D$. Line $C$, which has the equation $y = mx + 1$, intersects line $A$ and $B$ at $D$, and the line $y = ax$ is perpendicular to line $C$. Find $m + a$ as a common fraction.