Iain has 200 pennies. He realizes that 30 of his pennies are older than he is. If he wishes to get rid of these pennies and then throw out 20% of his remaining pennies, how many will he have left?
Start with taking out the older pennies 200 pennies - 30 pennies = 
<gadget id="calculator">200-30</gadget>
<output>170</output>
170 pennies.
Take the 170 pennies * .20 = 
<gadget id="calculator">170*.20</gadget>
<output>34</output>
34
170 pennies - 34 pennies = 
<gadget id="calculator">170-34</gadget>
<output>136</output>
136 pennies.

<result>136</result>