Help interpreting a momentum graph

[yamugushi]

Homework Statement

What is the objects momentum at 3 seconds, on the graph at 3 seconds it is exerting 35n

Homework Equations

f=change in momentum/time

The Attempt at a Solution

I got 105kgms but it was marked wrong...
I can make the graph in paint if it will help anybody.

 

[rock.freak667]

It would be beneficial to post the graph as well.

 

[yamugushi]

ok:

 

[rock.freak667]

then simply the area under the graph gives the change in momentum, so from t=1 to t=3 find the area. It forms a rectangle and triangle.