I am so confused with this question...

dy/dt = (-pi*cos(pi*t)-2ty)/(1-t^2): f(t,y), y(0) = 0

y(h) = -pi*h + [pi(pi^2 + 6)/6]*h^3 + y^(iv)(c)/24 h^4

y^(iv) is the fourth derivative I have to find the absolute local truncation error. The answer is just:

[pi(pi^2 + 6)/6]*h^3 + y^(iv)(c)/24 h^4

I just don't know how they got it if someone could explain