Question 917427
h = -16t^2+32 t
when h= 12 
12 = -16t^2+32 t
    subtract 12 on both sides
 12-12 =-16t^2+32t-12
 0 =-16t^2+32t-12
solve the quadratic equation
*[invoke quadratic "t", -16, 32, -12 ]
   so t is 0.5 &1.5