The height h (in feet) above the water of a cliff diver is modeled by h=-16t^2+8t+80, where t is the time (in seconds). how long is the diver in the air?

If this is algebra, then you will be using a parabola to solve this problem:
t=-b/2a
t=-8/2(-16) = 8/-32 = -1/4
t=-1/4=-0.25
h=-16(0.0625)+8(-0.25)+80
h=1-2+80
h=79
(-0.25,79)
then plug this ordered pair above and draw a line directly down the middle of it to use as a "mirror" and plug 2 different numbers(preferably 0 and 1) into the variable t to find the other two points and then reflect the two points over the "mirror" to get the last two points to graph your paprabola