Donna bought 3 times as many pencils as Marcia did. Marcia bought double the number of pencils as Cindi did. How many pencils did Donna and Marcia buy altogether if Cindi spent $30 on $0.50 pencils?
Cindi bought 30/0.50 = <<30/0.50=60>>60 pencils.
Marcia bought 2*60 = <<2*60=120>>120 pencils.
Donna bought 3*120 = <<3*120=360>>360 pencils.
Altogether, Donna and Marcia bought 120+360 = <<120+360=480>>480 pencils.
#### 480