If there 20 gnomes in Westerville woods, the Ravenswood forest has 4*20=<<20*4=80>>80 gnomes.
If 40% of gnomes in the Ravenswood forest are taken for use by the owner of the forest, the number of gnomes will reduce by 40/100*80=<<40/100*80=32>>32
The number of gnomes that will remain is 80-32=<<80-32=48>>48
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