If they ate 60% of the pieces of cake, the friends ate 60/100 * 240 pieces = <<60/100*240=144>>144 pieces of the cake.
The total number of pieces remaining is 240 pieces - 144 pieces = <<240-144=96>>96 pieces
When Juelz divided the remaining pieces of cake to his sisters, each sister received 96 pieces / 3 sisters = <<96/3=32>>32 pieces/sister
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