Tom plants a tree that is 1 year old and 5 feet tall.  It gains 3 feet per year.  How old is it when it is 23 feet tall?
It has grown 23-5=
<gadget id="calculator">23-5</gadget>
<output>18</output>
18 feet.
So it is 18/3=
<gadget id="calculator">18/3</gadget>
<output>6</output>
6 years older.
That means it is 6+1=
<gadget id="calculator">6+1</gadget>
<output>7</output>
7 years old.

<result>7</result>