How can I plot the contours with label for the following?

The Code is as follows:

z := -y + sech(x - 3*t);

w := 10*sech(x - 3*t);

with(plots);

P1 := plot(eval(w, t = 0), x = -10 .. 10):
P2 := contourplot(eval(z, t = 0), x = -10 .. 10, y = -eval(w, t = 0) .. eval(w, t = 0), contours = 5, grid = [101, 101]):
display(P1, P2);

Thanks

How can I analytially evaluate the following definite integral ?

int(1/(c*x + d), x = a .. b)

My Output is as follows:

Thanks.