Q: If the price of an article is reduced by 30% and the sales of the article increase by 50%, what is the percentage change in the total amount of receipts?
we can define a variable "z" as the net percent change in receipts and
set up the following equation:
z = (x + y + xy/100)%
= (-30 + 50 + (-30 * 50)/100)%
= 5%
This equation shows that the net percent change in receipts is 5%.