Math Problem, I need help.?

Question

An electronic device that previously sold for $21 has been reduced to $17.43. The price
reduction, rounded to the nearest whole percent, is
A. 17%. C. 21%.
B. 20%. D. 83%.

How did you figure it out?? I need some help! Thanks!

Answer 1

Subtract $21 - $17.43 = $3.57
Divide that answer by $21

So $3.57 / 21 = .17 which is 17% (A.)

Answer 2

$21.00 is 100% of the total price. Write $21.00/100. The device was reduce to $17.43. You need to subtract $17.43 from $21.00 to find the actual price reduction. We will call that number #. To find the percent of the reduction we will make a comparison, cross multiply, and divide.

so $21.00/100 = # / X . (Remember that # represents the actual price reduction. X is the unknown percentage.

Cross multiply -- #*100 = Y
Divide Y by 21 to get the percentage.

Now, remember to round your answer. If the number to the right of the decimal point is less than 5, stay where you are. If the number is 5 or greater, round up.
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$21.00 - $17.43 = $3.57

$21.00/100 = $3.57/X
$3.57*100 = 357
357/21 = 17

No need to round this answer.

Your answer should be 17.43 is a 17% price reduction.

These are my very favorite math problems. Just remember to keep like elements in the same part of the fraction comparison. For example, money amounts go on the top, percentages go on the bottom. If you put the percentages on the top, that's ok. Just keep them BOTH on top.

It would look like this:

$21.00 .... $3.57
______ = _____

100 % ...... ?

Cross multiply: $3.57 times 100
Divide by the other known number: 357 divided by 21
The answer is the percentage that $3.57 represents: 17 %

(I had to put in .....'s to expand the space between numbers, not for a mathematical reason.)

Answer 3

Convert the percentages in to decimals and then multiply each decimal by 21. Take the answers u get and subtract them one at a time from 21. Whichever equals 17.43 is your answer! In case u need help w/ decimals, heres the general idea... 100%= 1 90%= .9, 80%= .8, 5%= .05 etc.

Answer 4

a 17%

u divide 17.43 by 21 and make the decimal a percent and round

Answer 5

21 - 17.43 = 3.57
3.57 / 21 = .17
move the decimale two places to the right and you get 17%

Answer 6

i would do it like this:

if $21-------------100%
$(21-17.43)-------- X
21-17.43=3.57
X=(3.57*100)/21=17%