Mandy is 3 years old. Her brother is 4 times as old as she is. Her sister is 5 years younger than her brother.  What is the age difference between Mandy and her sister?
Mandy's brother's age is 3 years x 4 = 
<gadget id="calculator">3*4</gadget>
<output>12</output>
12 years old.
Her sister's age is 12 years - 5 years = 
<gadget id="calculator">12-5</gadget>
<output>7</output>
7 years old.
The age difference between Mandy and her sister is 7 years - 3 years = 
<gadget id="calculator">7-3</gadget>
<output>4</output>
4 years.

<result>4</result>