that is height
h=16t^2+16t+480
when h=0 is when it hits the water
0=16t^2+16t+480
undistribbute 16 for ease
0=16(t^2+t+30)
16*0=0 so assume
t^2+t+30=0
factor
(t+6)(t-5)=0
set to zero
t+6=0
minus 6
t=-6
false, since you cannot have negative time
t-5=0
add 5
t=5
at t=5 she hits the water
5 seconds
