The movie theater admission costs $8 - $3 = $<<8-3=5>>5 before 6 P.M.
Kath will pay for herself, her siblings, and her friends, so that is a total of 1 + 2 + 3 = <<1+2+3=6>>6 people.
So, Kate will pay $5 x 6 = $<<5*6=30>>30 for all their admission.
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