It takes 7 years for an apple tree to bear fruit. If Lydia planted a tree when she was 4 years old and is now 9 years old, how old would she be when she gets to eat an apple from her tree for the first time?
The tree has been planted for 9 - 4 = 
<gadget id="calculator">9-4</gadget>
<output>5</output>
5 years.
It will take another 7 - 5 = 
<gadget id="calculator">7-5</gadget>
<output>2</output>
2 years for it to bear fruit.
Lydia will be 9 + 2 = 
<gadget id="calculator">9+2</gadget>
<output>11</output>
11 years old.

<result>11</result>