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Thread: Given a = c - d / 2ed, find a for c = 20, d = 10, e = 2

  1. #1

    Given a = c - d / 2ed, find a for c = 20, d = 10, e = 2

    This is driving me crazy:

    Use the following formula to calculate a, if c = 20, d = 10 and e = 2:

    . . . . .a = c d/2e
    Last edited by stapel; 01-31-2018 at 04:36 PM. Reason: Creating useful subject line.

  2. #2
    Elite Member mmm4444bot's Avatar
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    Quote Originally Posted by goldenmonkey View Post
    a = c d/2e
    Because there are no grouping symbols around the denominator, your typing means this:

    [tex]a = c - \dfrac{d}{2} \; \cdot \; e[/tex]

    I'm thinking maybe you meant this, instead:

    a = c - d/(2e)

    These grouping symbols show that 2e is a denominator:

    [tex]a = c - \dfrac{d}{2e}[/tex]


    It's important to type grouping symbols around numerators or denominators that contain more than one number or symbol. Otherwise, people can't be sure which way to go.

    So, what happened, when you substituted the given values for the given symbols? Did you then try the arithmetic? For example, the equation c=20 tells us that we can replace symbol c with the number 20, anywhere we see it. That's called 'substitution'. Once you substitute all of the given values, do the arithmetic.

    Need more help? Please show us what you tried (even if you think it's wrong).

    Also, be sure to read the forum guidelines.



    Here's a short video lesson.


    Last edited by mmm4444bot; 01-29-2018 at 03:46 AM. Reason: added video lesson
    "English is the most ambiguous language in the world." ~ Yours Truly, 1969

  3. #3

    Thank you

    This was in an entrance exam to a diploma in financial planning, as far as I'm concerned the answer is 10. However that's not their take on it. Insisting the answer is 17.5. I understand that with the brackets that would change it but this is exactly how the equation was presented to me.

    Use the following formula to calculate a, if c = 20, d = 10 and e = 2.
    a = c d/2e

  4. #4
    Elite Member mmm4444bot's Avatar
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    Quote Originally Posted by goldenmonkey View Post
    as far as I'm concerned the answer is 10. However that's not their take on it. Insisting the answer is 17.5. I understand that with the brackets that would change it but this is exactly how the equation was presented to me.

    Use the following formula to calculate a, if c = 20, d = 10 and e = 2.
    a = c d/2e
    I agree with you. As presented, the answer is 10.

    I parse the expression d/2e as d/2 e because the Order of Operations tells us to do multiplication and division together in the order they occur, reading from left to right.

    We do d/2 first, then we multiply that by e.

    In order to obtain 17.5, there has to be a change to the Order of Operations. They made a mistake, by not printing grouping symbols to clearly indicate the denominator, that is, to force 2e to be done before dividing d.

    a = c - d/(2e) = 35/2 (or, 17.5 in decimal form)
    Last edited by mmm4444bot; 01-29-2018 at 03:44 AM. Reason: minor rewordings, and fixed typos
    "English is the most ambiguous language in the world." ~ Yours Truly, 1969

  5. #5
    I agree with you. As presented, the answer is 10.

    I parse the expression d/2e as d/2 e because the Order of Operations tells us to do multiplication and division together in the order they occur, reading from left to right.
    Well I can sleep tonight.

    Thank You.
    Last edited by mmm4444bot; 01-29-2018 at 03:43 AM. Reason: fixed typo in quote

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