CALCULATING ORIGINAL PRICE LESSON PLAN
If you know the amount of a discount and the % of the discount, how can you calculate the original price? Let’s look at this question in a little more detail.
First, you know what you paid for the item. Let’s say you paid $18.00.
Then, you also know the discount was 40%.
How can we use these two numbers to calculate the original price of the item?
If we have the sales price and the % of the discount, we have all that we need to do this calculation.
The first thing that we are going to need to do is to write an equation.
Here is how we can reword this problem:
18 is 40% of what number?
This is saying that after we took a discount of 40% from some number and ended up with 18.
Let’s write the equation.
“18 is” becomes 18 =
40% becomes a decimal .40
“of” means to multiply
What number is our unknown x?
Here is the equation.
18 = .40x
Next, we need to get x alone, so we divide both sides of the equation by .40.
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