Alvin is 30 years old and Simon is 5 years away from being 1/2 the age of Alvin.  How old is Simon?
1/2 the age of Alvin who is 30 is 30/2 = 
<gadget id="calculator">30/2</gadget>
<output>15</output>
15.
Simon is 5 years away from being half the age of Alvin so Simon is 15-5 = 
<gadget id="calculator">5+5</gadget>
<output>10</output>
10 years old.

<result>10</result>