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?
Betty's daughter is 40/100 * 60 = 
<gadget id="calculator">40/100*60</gadget>
<output>24</output>
24 years younger than she is.
That means her daughter is 60 - 24 = 
<gadget id="calculator">60-24</gadget>
<output>36</output>
36 years old.
So the granddaughter is 1/3 * 36 = 
<gadget id="calculator">1/3*36</gadget>
<output>12</output>
12 years old.

<result>12</result>