There are 21 cherry tomatoes on the tomato plant.  2 birds eat one-third of the tomatoes.  How many are still left on the tomato plant?
The birds eat this many tomatoes: 21 / 3 = 
<gadget id="calculator">21/3</gadget>
<output>7</output>
7 tomatoes.
There are this many tomatoes left on the plant: 21 - 7 = 
<gadget id="calculator">21-7</gadget>
<output>14</output>
14 tomatoes.

<result>14</result>