If a car goes along a straight road heading east and speeds up from 45ft/s to 60ft/s in 5s , calculate the acceleration

Acceleration = change in velocity/ time = (final velocity - initial velocity)/time 

accel = (60ft/s - 45ft/s)/5s = 3 ft/s

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.