Q 6.2   p.141

#a

go = 10 /(s + 4)
gc = go/(1 + go);
yt1 = InverseLaplaceTransform[gc/s, s, t]

#b

go = 10/(s + 4)/s
gc = go/(1 + go);
yt2 = InverseLaplaceTransform[gc/s, s, t]

summary

Plot[{yt1, yt2}, {t, 0, 4}, PlotRange ->  {0, 1.2}, 
      PlotStyle ->  {Hue[0.9], Hue[0.7]}]