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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 two digit number is seven times the sum of its digits. The number formed by reversing the digits is 18 less than the original number. Find the original number.

    A)  86                               

    B)  64            

    C)  75                               

    D)  42

    Correct Answer: D

    Solution :

    (d): \[10a+b=7\left( a+b \right)\] \[\Rightarrow 3a=6b\Rightarrow a=2b\] \[10b+a\,\,\text{or}\,\,10b+2b=\left( 10a+b \right)-18\] Or \[12b=\left( 20b+b \right)-18\] Or \[18=9b\Rightarrow b=2;a=4\] \[\Rightarrow 7\left( a+b \right)=42.\]


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