Answer:
The graph is missing, but ill try to answer this anyway.
The acceleration is the rate of change of the velocity; this means that if you know the velocity as a function of time; v(t), you can obtain the acceleration a(t) by differentiate v(t) with respect to time; this is:
a(t) = dv(t)/dt
Them if you have a graph of velocity versus time, you can find the equation of v(t) and then find the acceleration.
For example, if your graph of velocity vs time is a linear relation, then the acceleration will be the slope of the linear relation.