Slide 30: The equation should be
x(t) = 4 cos(2 pi 100 t + 3 pi / 4) + 2 cos(2 pi 200 t) + 5 cos(2 pi 300 t + 3 pi / 5)
.
Slide 31: The equation here should be the same as above.
Slide 15: Term Ts is missing from the last 2 equations.
Slide 16: Term Ts should also appear in the 3 equations for x[n].