The Height of a Projectile Fired Vertically into the Air $-$

The height of a projectile fired vertically into the air (neglecting air resistance) at an initial velocity of 64 feet per second is a function of the time and is given by the equation f ( x ) = 64 x $-$ 16 x 2 , where x represents the time. Find the highest point reached by the projectile. __________ feet