3.9 Finding a Value After an Increase and Decrease

To examine the outcome of increase or decrease in transaction, we need to understand the basic calculations involved. Increase problems are indicated by phrases such as after “an increase of”, “more than” or “greater than”. Decrease problems are indicated by phrases such as “after a decrease of”, “less than” or “after a reduction of”. The original value (base) is always the original amount, (100%) before any increase or decrease takes place.

Example 14
This year’s sales are RM 151,555 which is 10% more than last year’s sales. Find last year’s sales.

Solution:

3.9 Finding a Value After an Increase and Decrease

Example 15
Album sales were up 4% from last year’s sales to RM 285.2 million. Find last year’s sales.

Solution:

3.9 Finding a Value After an Increase and Decrease

Example 16
Ellin’s sales figures have increased exactly 20% per year for the last two years. Her sales this year are RM 126,720. Find her sales two years ago. (Hint: the two 20% cannot be added together, because of 2 separate years, therefore 2 separate bases)


Solution:

3.9 Finding a Value After an Increase and Decrease

Example 17
After a deduction of 10% from the original price, a customer paid RM 126 for a designer skirt. Find the skirt’s original price.

Solution:

3.9 Finding a Value After an Increase and Decrease

Example 18
After Fleet feet deducted 10% from the price of a pair of sneakers, Nancy had to pay RM 180. What was the original price of the sneakers?

Solution: