A 400 suit is on sale for 20% off. You have a coupon for an additional 30% off.

Question

Use decay factors to find the price of the suit.

Answer 1

If the suit is on sale for $400, and that amount is 20% off its original price, then it started at $500.

Taking the successive discounts, $500×.8=$400 for the 20%, and then $400×.7 =$280 for the additional 30%

I am unable to produce the $276.

Answer 2

There are two ways find a sale price.

First convert the %s to decimals.  Then:

1) You can find the % off and subtract it from the original price.

     $400 X 0.2  and then subtract that amount from $400

2) Or you can subtract the % off from 100% and multiple that times the original price.

      (100% - 20%) = 0.8 x $400

Then you have the additional problem of another discount.

You can calculate the price after 20% off and then take 30% off of that.

Multiplication is the same no matter what order you do in it.

So you can do the 20% first then 30%, or you can do the 30% first.