There were 21 dollars in the cookie jar. Doris spent $6 from the cookie jar. Martha spent half as much as Doris. How much money, in dollars, was left in the cookie jar?
Martha spent 6/2=
<gadget id="calculator">6/2</gadget>
<output>3</output>
3 dollars.
Martha and Doris spent 6+3=
<gadget id="calculator">6+3</gadget>
<output>9</output>
9 dollars.
There were 21-9=
<gadget id="calculator">21-9</gadget>
<output>12</output>
12 dollars left in the cookie jar.

<result>12</result>