Betty is 60 years old, and she is the oldest person in the family. Her daughter is 40 percent younger than she is, and her granddaughter is one-third her mother's age. How old is the granddaughter?
How old is Betty's daughter? ** Betty's daughter is 40/100 * 60 = <<40/100*60=24>>24 years younger than she is.
How old is Betty's daughter? ** That means her daughter is 60 - 24 = <<60-24=36>>36 years old.
How old is Betty's granddaughter? ** So the granddaughter is 1/3 * 36 = <<1/3*36=12>>12 years old.
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