John weighs 220 pounds when he starts exercising.  He manages to lose 10% of his body weight.  He then gains back 2 pounds.  How much does he weigh at the end?
He lost 220*.1=
<gadget id="calculator">220*.1</gadget>
<output>22</output>
22 pounds.
So after gaining some weight back he was 22-2=
<gadget id="calculator">22-2</gadget>
<output>20</output>
20 pounds lighter than before.
So his weight is 220-20=
<gadget id="calculator">220-20</gadget>
<output>200</output>
200 pounds.

<result>200</result>