Diana is twice as old as Grace is today. If Grace turned 3 a year ago, how old is Diana today?
Today, Grace is 3 + 1 = 
<gadget id="calculator">3+1</gadget>
<output>4</output>
4 years old.
So, Diana is 4*2 = 
<gadget id="calculator">4*2</gadget>
<output>8</output>
8 years old today.

<result>8</result>