Maximum of Quadratic

Algebra Level 1

Consider the quadratic function

$y=ax^2+bx+c,$

where $a$ , $b$ and $c$ are constants. If $y$ has a maximum value of $54$ , and the graph of $y$ passes through the two points $(-2, 0)$ and $(4, 0),$ what is the value of $a+b+c?$