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# How can i solve to get the total price?

A suit is on sale for \$400 and is on sale for 20% off. You present a coupon at the register for an additional 30% off. Use the decay factors to determine the price you pay for the suit

### 2 Answers by Expert Tutors

Kay G. | ~20 Years Accounting Tutoring Experience~20 Years Accounting Tutoring Experience
4.9 4.9 (32 lesson ratings) (32)
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I've never heard of a decay factor method.  I looked it up and everything I saw seemed to relate it as a decay over a period of time, like the opposite of an exponential growth.  I saw nothing related to a question like this.  However, since what I saw seems to be essentially the proportion of what you'd have after you got done "decaying," the following method I know might be appropriate:

If we assume Emily is correct that \$400 is the original price, you can do this as one percent which is sometimes taught in business math classes.  It still uses the 80% and the 70%, but it's a way of finding one percent you can use rather than doing them one at a time.

You would take .80 x .70 = .56.  (56%)

I know this as a "cost equivalent," because you pay the equivalent of 56% of the original price.

You can then just multiply 400 x .56.

(The nice thing about this method is that once you have the 56%, you can use it on any original cost without doing two multiplications.)
Emily W. | Math Tutor - GRE SAT ACT ASVAB K-12Math Tutor - GRE SAT ACT ASVAB K-12
5.0 5.0 (20 lesson ratings) (20)
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Hi Olivia,

First the wording of this question is off, but I believe that I know what you meant. I will solve it in the manner that I believe is desired (with the suit being originally \$400, not on sale for \$400).

For the first discount of 20% you would multiply \$400 X 0.8 = \$320.

(Note: you could multiply by 0.2 which would give you the 20% off and then subtract that value from \$400)
(Thus \$400 X 0.2 = \$80 off and then \$400 - \$80 = \$320. I just did a shorter step by doing the above.)

Then to address the additional 30% off you would take your new price (\$320) and multiply it by 0.7 to find your total afterwards/
\$320 X 0.7 = \$224

(Note: my rational for using 0.7 can be made using the same argument as before)

Therefore your total comes to \$224 after both discounts.

Hope this helps!

Emily