Finding this displacement on a v/t graph

[jeffc93]

Homework Statement

there's a picture of the graph and i need to determine the displacement of the object within the first 18seconds of it. (in meters)

Homework Equations

area below line is displacement (i thought?)

The Attempt at a Solution

i just did some basic things:

i found the height which is 18.

and then i found the areas of all the triangles and rectangles under the line and added them up and got 171 or -171 but its not right

any help?

any help would be greatly appreciated, therefore i could do the rest on my own :)

 

[tiny-tim]

Welcome to PF!

Hi jeffc93! Welcome to PF!

area below line is displacement (i thought?)

Nope …

area between line and horizontal axis (with areas below the axis counting as negative) is displacement.