She spends this long researching and editing her essay 45 min + 75 min = <<45+75=120>>120 min.
Converting the minutes to hours for researching and editing is 120 / 60 = <<120/60=2>>2 hours.
She spends this long writing the essay 6 x 30 min = <<6*30=180>>180 min.
Converting the minutes to hours for writing the essay is 180 / 60 = <<180/60=3>>3 hours.
The total hours Rachel spends completing the essay is 2 + 3 = <<2+3=5>>5 hours.
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