Question 121302
h(t) = -16t^2 + 20t + 100
80 = -16t^2 + 20t + 100
0 = -16t^2 + 20t + 20
0 = -4t^2 + 5t + 5
t = ( -5 +- sqrt( 25 + 4*4*5 ) ) / (-2*4)
t = ( 5 +- sqrt( 105 ) ) / 8