Question

You are buying potato chips at the grocery store. You have a manufacturer’s coupon for $1.00 off and the store is offering 20% off if you buy 2 bags. How do you compute your final cost?

Answer 1

Answer:

Hence, the final cost of the bags will be:

$ (0.8x-1)

Step-by-step explanation:

Let the cost of 1 bag of potato chips be $ x.

Then cost of 2 bags of potato chips will be: $ 2x

Now after buying two bags the store is offering 20% off.

That is we have to pay 80%(=80/100=0.8) of the total amount after the discount.

i.e. The cost after discount is:

0.8 of x

=0.8x

Now, We have a manufacturer’s coupon for $1.00.

Hence, the final cost of the bags will be:

$ (0.8x-1)

Answer 2

You take your cost of the chips (Lets say it is 2.50 a bag so $5 for two bags).
20% off means it will be at 80% of the full price so you multiply 

5 x 0.8 = 4

Now if you add in  the discount of your $1 coupon, you have 4 - 1 = 3 so your final answer would be $3. 

(Keep in mind, I was given no cost for the chips so I made one up. This is just to explain the procedure.)