Bantu jawabbb dengan cara ya... :)

Beli 3 lusin buku = 64.800
Jual 2 lusin buku = 2.100/buah = 2.100 x (2 x 12) = 50.400
Jual 1 lusin buku sisanya = 1.700/buah = 1.700 x 12 = 20.400
%untung = [(Total harga jual - harga beli) / harga beli] x 100%
= {[(50.400 + 20.400) - 64.800]/64.800} x 100%
=[(70.800-64.800)/64.800] x 100%
= 9,25%