I used the points for t-0 and t-7 and came up with the three shapes on the graph..(the rectangle the trapezoid and the triangle) and then solved for their area under the curve and then combined.
I don't have a scanner to post the graph that I drew the shapes on.
1. What is the displacement between t= 0 s and t= 7 s?The "area' under the curve, between the two times is the displacement. The "area" is the area enclosed by the curve and the time axis (v=0 line). Those parts of the curve with negative velocity contribute negative area and those with positive...