Alice is 7 years older than Beth, who is 5 years older than Erica. What is the difference between the ages of Alice and Erica, if Erica is 30 years old?
Beth is 30+5 = 
<gadget id="calculator">30+5</gadget>
<output>35</output>
35 years old.
Alice is 35+7 = 
<gadget id="calculator">35+7</gadget>
<output>42</output>
42 years old.
The difference between the ages of Alice and Erica is 42-30 = 
<gadget id="calculator">42-30</gadget>
<output>12</output>
12 years.

<result>12</result>