20 x 1/4 = <<20*1/4=5>>5 dolphins are fully trained.
So, 20 - 5 = <<20-5=15>>15 dolphins are not yet fully trained.
15 x 2/3 = <<15*2/3=10>>10 are currently in training.
Therefore, 15 - 10 = <<15-10=5>>5 dolphins will be trained next month.
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