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  3. 8th Class
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  5. Linear Equations in One Variable

8th Class Mathematics Linear Equations in One Variable Question Bank Linear equations in One Variable

  • question_answer
    A number consists of two digits whose sum is 9. If 27 is subtracted from the original number, its digits are interchanged. Then the original number is _____.

    A)  53                  

    B)         45                  

    C)  92                  

    D)         63      

    Correct Answer: D

    Solution :

    Let units place digit be x. So tens place digit\[=9-x\]. \[\therefore \] The original number =10(9-x)+x = 90-10x + x=90 - 9x Now, after interchanging the digits, the number formed = 10 (x) + 9 - x = 9x + 9 \[\therefore \] According to question, we have 90 - 9x - 27 = 9x + 9 \[\Rightarrow -18x=-54\Rightarrow x=3\] So, the original number \[=90-9\times 3=63\]


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