Delete the element in the list

Hello all. I want to ask about deleting elements of the Subset child set that are in the Parent object set

Eg: I have set ssg1 include ((5 10) (15 20)) and set ssg include ((5 10) (15 20) (25 30) (35 40))

I want to create a new ssg file that deletes the elements of ssg1 in ssg: the result returns ssg ((25 30) (35 40))

Please help me!

(setq a '((5 10) (15 20))
     b '((5 10) (15 20) (25 30) (35 40))
     c (vl-remove-if '(lambda (u) (member u a)) b)
     )

Maybe like this :

[b][color=BLACK]([/color][/b]defun remove [b][color=FUCHSIA]([/color][/b]expr lst[b][color=FUCHSIA])[/color][/b][color=#8b4513];;;TonyT or VNesterowski[/color]
 [b][color=FUCHSIA]([/color][/b]apply 'append [b][color=NAVY]([/color][/b]subst nil [b][color=MAROON]([/color][/b]list expr[b][color=MAROON])[/color][/b] [b][color=MAROON]([/color][/b]mapcar 'list lst[b][color=MAROON])[/color][/b][b][color=NAVY])[/color][/b][b][color=FUCHSIA])[/color][/b][b][color=BLACK])[/color][/b]

[b][color=BLACK]([/color][/b]defun c:foo [b][color=FUCHSIA]([/color][/b][b][color=FUCHSIA])[/color][/b]
 [b][color=FUCHSIA]([/color][/b]setq ssg1 '[b][color=NAVY]([/color][/b][b][color=MAROON]([/color][/b]5 10[b][color=MAROON])[/color][/b] [b][color=MAROON]([/color][/b]15 20[b][color=MAROON])[/color][/b][b][color=NAVY])[/color][/b][b][color=FUCHSIA])[/color][/b]
 [b][color=FUCHSIA]([/color][/b]setq ssg  '[b][color=NAVY]([/color][/b][b][color=MAROON]([/color][/b]5 10[b][color=MAROON])[/color][/b] [b][color=MAROON]([/color][/b]15 20[b][color=MAROON])[/color][/b] [b][color=MAROON]([/color][/b]25 30[b][color=MAROON])[/color][/b] [b][color=MAROON]([/color][/b]35 40[b][color=MAROON])[/color][/b][b][color=NAVY])[/color][/b][b][color=FUCHSIA])[/color][/b]

 [b][color=FUCHSIA]([/color][/b]foreach p ssg1
   [b][color=NAVY]([/color][/b]setq ssg [b][color=MAROON]([/color][/b]remove p ssg[b][color=MAROON])[/color][/b][b][color=NAVY])[/color][/b][b][color=FUCHSIA])[/color][/b]

 [b][color=FUCHSIA]([/color][/b]prin1 ssg[b][color=FUCHSIA])[/color][/b]
[b][color=FUCHSIA]([/color][/b]prin1[b][color=FUCHSIA])[/color][/b][b][color=BLACK])[/color][/b]

-David

thank you all very much. nice