Question 49206
 h= -16t^2 +112t 
 180=-16t^2 +112t
 180-180 = -16t^2 +112t -180 
 -16t^2 +112t -180 = 0
.
{{{x = (-(112) +- sqrt( (112^2)-(4)(-16)(-180) ))/((2)(-16)) }}} 
.
t = 2.5 or t = 4.5