Finding Original Amounts with Percent Change

This video tutorial teaches how to find the original amount and the amount of change given the percent of change and the final amount. It uses an example involving a couch purchase with sales tax to demonstrate solving the problem using both proportions and equations. The tutorial also reviews solving proportions and equations, clarifies common misconceptions about percent change, and provides step-by-step solutions to the example problem.

What is the main problem discussed in the video?

• Calculating the final amount after tax

• Learning how to calculate interest rates

• Finding the original amount and the amount of change given the percent of change and the final amount

• Understanding how to apply discounts

Which of the following is NOT a common mistake when dealing with percent change?

• Calculating the percent change before finding the original amount

• Assuming the percent change is the same as the amount of change

• Confusing the final amount with the amount of change

• Using the wrong formula for percent change

What method is used to find the original amount using proportions?

• Division and multiplication

• Addition and subtraction

• Substitution

• Cross-multiplication

How do you find the amount of tax using proportions?

• Add the tax rate to the original amount

• Divide the final amount by the tax rate

• Multiply the original amount by the tax rate

• Subtract the original amount from the final amount

Which method involves using cross products to find the original amount?

• Equation method

• Proportion method

• Graphical method

• Substitution method

What is the first step in using equations to find the original amount?

• Multiply the final amount by the percent

• Convert the percent to a decimal

• Add the percent to the final amount

• Subtract the percent from the final amount

How is the percent converted to a decimal in the equation method?

• By multiplying the percent by 100

• By moving the decimal point two places to the left

• By dividing the percent by 10

• By adding 100 to the percent

What is the final step in solving the equation for the original amount?

• Subtract the tax from the final amount

• Multiply both sides by the percent

• Divide both sides by the decimal equivalent of the percent

• Add the original amount to the tax

What is the relationship between adding a percent and the original amount?

• Adding a percent is the same as dividing the original amount by the percent

• Adding a percent is the same as finding that percent of the original amount

• Adding a percent is the same as multiplying the original amount by 100

• Adding a percent is the same as subtracting it from the original amount

What is the purpose of the lesson in the video?

• To demonstrate how to apply sales tax

• To teach how to calculate discounts

• To explain how to find the original amount given the percent of change and the final amount

• To show how to solve complex equations