Answer:
177.3 feet
This is a classic find the vertex of a parabola question.
if this was a calculus class the solution would be to take the derivative and set it equal to zero... -32t+ 105 = 0
BUT i assume that you are not in a calculus class..
so we try plan "B" the highest (or lowest) point of parabola is it's vertex
the vertex formula is [-b/2a,f(-b/2a)]
in your problem a = -16, b=105, c= 5
so the "X" (TIME) is located at -(105)/(2*-16) = 3.28
plug in 3.28 into -16(3.28)^2 + 105(3.28) + 5 = 177.27
and you will get
Explanation: