A roast chicken is discounted by 30%, then by 10%. What is the overall discount?
Let's assume that it ws a valuable chicken, worth $100.00.
Discounting this chicken by 30% give us a chicken worth 70% of $100.00
---> 0.70 x $100.00 = $70.00
Now we discount the $70.00 by another 10%
---> 0.90 x $70.00 = $63.00
Our final price of $63.00, when compared to our original price of $100.00:
---> $63.00 / $100.00 = 0.63, or 63%.
[The final percentage would be the same no matter what we chose for an original value.]