Sammy can eat 15 pickle slices.  His twin sister Tammy can eat twice as much as Sammy.  Their older brother Ron eats 20% fewer pickles slices than Tammy.  How many pickle slices does Ron eat?
Tammy can eat twice as many pickle slices as Sammy who eats 15 so Tammy can eat 15*2 = 
<gadget id="calculator">15*2</gadget>
<output>30</output>
30 pickle slices.
Ron eats 20% fewer pickle slices than Tammy who eats 30 pickle slices so that's .20*30 = 
<gadget id="calculator">20*.01*30</gadget>
<output>6</output>
6 fewer slices than Tammy.
Tammy eats 30 slices and Ron eats 6 less, then Ron eats 30-6 = 
<gadget id="calculator">30-6</gadget>
<output>24</output>
24 pickle slices.

<result>24</result>