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.