Stockmoose,
You don't replace one variable with anything when you are doing the calculations from the answer choices. All you're doing is plugging in numbers.
When you are doing your first calculation is when you consider "replacing." The fact is, for this question at least, there is no replacing. What you're doing is if you said Z = 100 and X = 25 and Y = 20 is your saying 25% of 100 which .25(100) or (25/100)(100) which both equal 25. But it is 25 +100 because "it was marked up." Then you will take 20 percent of 125 which is .20(125) or 20/100 or 1/5(125) = 25 then you subtract 25 from 125 because they say it was discounted so the final answer is 100. You only use these percentage for your calculation.
When you are plugging in you don't use percentages for the calculation; you only use the numbers you chose for the variables. So for A you would put 10k(100) - [100(100)(25 -20)] - [100(25)(20)] all divided by 10k. Try it that way and see which answer yields the correct result.
You don't replace one variable with anything when you are doing the calculations from the answer choices. All you're doing is plugging in numbers.
When you are doing your first calculation is when you consider "replacing." The fact is, for this question at least, there is no replacing. What you're doing is if you said Z = 100 and X = 25 and Y = 20 is your saying 25% of 100 which .25(100) or (25/100)(100) which both equal 25. But it is 25 +100 because "it was marked up." Then you will take 20 percent of 125 which is .20(125) or 20/100 or 1/5(125) = 25 then you subtract 25 from 125 because they say it was discounted so the final answer is 100. You only use these percentage for your calculation.
When you are plugging in you don't use percentages for the calculation; you only use the numbers you chose for the variables. So for A you would put 10k(100) - [100(100)(25 -20)] - [100(25)(20)] all divided by 10k. Try it that way and see which answer yields the correct result.
















