Grace's age is 3/8th the age of her grandmother. Her grandmother is twice the age of Grace's mother. If Grace's mother is 80 years old, how old is Grace?
Grace's grandmother is 2 * 80 years = <<2*80=160>>160 years old.
Grace's age is 3/8 * 160 years = <<3/8*160=60>>60 years old.
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