Bush and Matt are brothers. Bush is younger than Matt by 3 years. This year Bush will be 12 years old. What will be Matt's age 10 years from now?
Bush is younger than Matt by 3 years, so if Bush is 12 years old then Matt is 12+3 = 
<gadget id="calculator">12+3</gadget>
<output>15</output>
15 years old.
In 10 years' time, Matt will be 10+15 = 
<gadget id="calculator">10+15</gadget>
<output>25</output>
25 years old.

<result>25</result>