How do I solve this?

The quadratic equation y = - 16t2+64f+ 2 represents the height of a projectile, y, in feet, at a particular time, I, in seconds. For what interval or intervals of time will the projectile be below 50 feet? 0 a.} Between 2 and 4 seconds 0 b.) Between 1 and 3 seconds 0 c.) Less than 2 seconds and greater than 4 seconds 0 cl.) Less than 1 second and greater than 3 seconds