Rebecca drinks half a bottle of soda a day. She bought three 6-packs of sodas the last time she was at the store. How many bottles of soda will she have left after four weeks?
Rebecca bought 3 * 6 = 
<gadget id="calculator">3*6</gadget>
<output>18</output>
18 bottles of soda.
A week is 7 days, so she will drink 4 * 7 = 
<gadget id="calculator">4*7</gadget>
<output>28</output>
28 half bottles of soda in four weeks.
A bottle is two half bottles, so she will drink 28 / 2 = 
<gadget id="calculator">28/2</gadget>
<output>14</output>
14 bottles of soda in four weeks.
Thus, after 4 weeks, she will have 18 - 14 = 
<gadget id="calculator">18-14</gadget>
<output>4</output>
4 bottles of soda left.

<result>4</result>