Percent increase and decrease

Percent increase is when you find a given percent of an amount and then add it to it.
Percent decrease is when you find a given percent of an amount and subtract it from it.

 One really important thing to remember about percent increase and decrease is that percent is always based on something, it doesn't stand alone, there is always something that it is "of" and with percent increase and decrease problems that is always the ORIGINAL amount.

There are three kind of percent increase and decrease problems and a good first step towards solving a problem is to decide which of them it is:
 1.Original amount, percent known, you want to find the new amount.
 If cost of life is running at 3%, how much would you need to live a year if your current expenditure is $920 per month?
 2.Original amount known, new amount known, you want to find out what percent the increase or decrease is. 
The value of Spain exports to Germany increased from €1480 million in 1987 to €2768 million in 1988. What was the percentage increase?
3.New amount known, percent known, you want to find the original amount.
 An item originally costing $20 is on a 10% off sale. What is the sale price? 


Solve the problems in a paper and write the answer as a comment.

See more information and examples here and here.

ALICIA