discount-formula-finding-the-discount-and-original-price

Interactive video lesson plan for: Discount Formula-Finding the Discount and Original Price

Activity overview:

Use the Discount Formula in order to find the discount price, and the original price.

Transcript
Welcome to MooMooMath where we upload a new Math video everyday.
Today this video covers how to work discounted prices and percents.
Example problem: What is the discounted price of a \$55 shirt
that has been marked down 15%?
You will often see this in stores for things on sale.
You can use the discount formula:
Original price-(original price times discount in decimal form) = Discounted price
Keep this in mind.
Here we go.
Original price = 55 - 55 times .15 equals the discounted price.
55 x .15 = 8.25
Now 55 - 8.25 = a discounted price of 46.75
Now there is a shortcut to this, if you like you can just multiply 55 times .85 which equal 1-15 =.85, and that will get you the same answer.
Sample problem two,
What is the discounted price of a \$45 watch marked down 10%?
Take the original price minus the original price times the decimal form of the percent, which is .10. and this equals the discounted price.
I know 45 x .10 = 4.50
Next we have 45 - 4.50 which equals 40.50
Again the shortcut method is to take 1 - .10 = .90
Next multiply .90 times 45 and it equals 40.50
The final problem is, "If the discounted price of a shirt that is marked down 20% is \$30, what was the original price?
Again, use the discount formula: " Original price-(original price times discount in decimal form) = Discounted price"
Now just fill in what we are given.
Original price is x, again the original price is x times the discount which is 20%, and I will write it as a decimal.
For the decimal I just move two places to the left, and this will equal our discounted price of \$30
x times .20 equals .20x. I will put a 1 in front of this x so you can see what I'm doing.
Bring the 30 down.
Combine like terms 1x-.20x equals .80x
Divide each side by .80.
Finally x equals 30 divided by .80, which equals 37.50
I can check this by multiplying by our shortcut and I can just multiply by .80 and it equals the discounted price of \$30
If you get your calculator out you can see that 37.50 times .80 equals 30.
So out original price equals \$37.50
Hope this helps. MooMooMath uploads new Math video everyday.

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Tagged under: percents,discounts,discounted price,discount formula,calculate sales price,sales price,math,moomoomath,original price

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