A tennis ball "A" is released from rest down a 10.0 m long inclined ramp with a uniform acceleration of 5.0 m/s2 . Another tennis ball "B" is initially located at the same height as ball "A" right above the lower edge of the ramp. Ball "B" is thrown upward with some initial speed at the same instant as the release of ball "A". A) What was the initial velocity of ball "B" so that "A" and "B" reach the bottom of the ramp at the same time?

You need to be more specific.  i really don't know what a "motion map" is.you can draw a graph of an object's position, distance, displacement, speed,velocity, or acceleration versus time, or you can draw a graph of the object's x-position versus its y-position and not give any information about time at all.if the graph presents position or displacement against time,  then constant velocity is a straight line . . i.e. a line that has  constant slope.if the graph shows speed against time, then constant velocityis a horizontal piece of line.if the graph shows acceleration against time, then constant  velocity is a piece of line that lies on the x-axis . . it's value is zero.