Anonymous
Anonymous asked in Science & MathematicsMathematics · 5 months ago

Math problem?

If a=5, b=3 and c=9

How is 

5a + 3b - c = 25

I get 23 using the rules of bidmas as follows:

(5x5) + (3x3) - 9

25 + 9 - 9

34 - 9

Am I doing it wrong using bidmas to solve? 

Any help to explain why I should subtract prior to addition, when it's that order, will be greatly appreciated. 

15 Answers

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  • sepia
    Lv 7
    5 months ago

    5a + 3b - c 

    = 25 + 9 - 9 (if a = 5, b = 3 and c = 9)

    = 25

  • 5 months ago

    5(5)+3(3)-9=25

    25+9-9=25

    25=25

    Math seems to be working today.

  • 5 months ago

    Are you doing the last subtraction correctly?

    34

    -9

    ----

    25

    I don't see where you get 23

    One other reminder about BIDMAS/BODMAS/PEMDAS or whatever mnemonic you are using.

    Multiplication and Division have equal precedence so when you are doing those operations, go left to right.

    Similarly, Addition and Subtraction have equal precedence, so when you do those, also go left to right.

  • 5 months ago

    sum of 

    9+(-9)=0

    can you see your mistake?

    you are not completing the process.

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  • 5 months ago

    34 - 9 = 25, not 23

  • 5 months ago

    5a + 3b - c = 25

    5(5) + 3(3) - 9

    25 + 9 - 9

    = 25 prove.

  • Bill
    Lv 6
    5 months ago

    5X5=25,3X3= 9 so 5a +3B =25 +9=  34-9 =25

  • 5 months ago

     If a = 5, b = 3 and c = 9 

     5a + 3b - c = 25

    How?

     (5×5) + (3×3) - 9

    = 25 + 9 - 9 

    = 34 - 9

     = 25

  • 5 months ago

    Technically, when adding and subtracting, you do so in order as they appear from left to right. This means that your steps are correct, meaning that it should look like this:

    5(5)+3(3)-9=25

           25+9-9=25

               34-9=25

                  25=25

          left side=right side

    ;)) 

  • How are you getting 23 from 34 - 9?  34 - 9 = 25

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