Answer
The inclusion of "$+20t$" increases the position x at which the particle stops.
Work Step by Step
Since velocity is the derivative of the position function,
it represents the SLOPE of the graph of x(t).
The particle will momentarily stop when the tangent to the curve is horizontal (slope=v=zero).
This happens at the vertex of each parabola in parts (e) and (f),
In part (f) we graphed the original (blue) and the shifted (red) graphs on the same coordinate system.
Please see the image below the text.
The vertex of the graph in (e) (the blue graph)
has a lower x value than the vertex in graph (f), (the red graph)
meaning that the inclusion of +20t, the value of x at which the particle stops
is increased.
(Remember, x is on the vertical axis here)
