Question 182203
If you know calculus, take the first derivative and solve when that is 0.

If all you have at your disposal is algebra, then use a different method.
Find the two points where the toy is 'on the ground (the values for t that result in S(t) = 0.
{{{-16t^2 + 128t}}}
{{{-16t(t-8)}}}
Set that to 0 and find the two values for t. t =0 and t = 8
SO the max point is hallfwya between them (t=4)
Solve S(t) at t=4 to find the max