The total percentage of those who rated Excellent or Very Satisfactory is 15% + 60% = 75%.
Seventy-five percent of the parents is 120 x 75/100 = <<120*75/100=90>>90.
Hence, 120 - 90 = <<120-90=30>>30 students rated either Satisfactory or Needs Improvement.
A total of 30 x 80/100 = <<30*80/100=24>>24 parents rated Satisfactory.
Therefore, 30 - 24 = <<30-24=6>>6 parents rated Needs Improvement.
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