
William W. answered 11/26/21
Experienced Tutor and Retired Engineer
If G'(t) = g(t) then G(t) = ∫g(t) dt and the integral is the area under the curve.
I'm assuming that the graph is g(t). To find G(t), find the area under the curve of g(t). You can typically use geometry to find the are under the graph of straight line segments. Use the initial information that G(0) = 4 so whatever area you get from 0 to 5, you would add 4 to it, whatever area you get from 0 to 10, add 4 to it, etc.