Quadradic Equation Word Problems - Examples & Practice

A hiker gets lost climbing a mountain by his home. In a fit of anger, he threw his GPS off the cliff (a VERY bad decision). His GPS follows the path of $y = -x^{2}+65x+750$, starting at a height of $y=750$ feet at $x=0$. How far did his GPS go before it landed at ground level, $y=0$? Give the positive answer of the quadratic.