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 = <T>divide(30, 0.5)=60.0 pencils.
Marcia bought 2*60 = <T>multiply(2, 60)=120 pencils.
Donna bought 3*120 = <T>multiply(3, 120)=360 pencils.
Altogether, Donna and Marcia bought 120+360 = <T>add(120, 360)=480 pencils.
