1.

Sum of the digits of a 2-digit number is 9. On reversing its digits, the new number obtained is 45re than the original number. Find the number​

Answer»

\sf\large\underline\purple{Let:-}

\tt{\implies The\: ones\:digit\:be\:x}

\tt{\implies The\:tens\:digit\:be\:y}

\tt{\implies The\: orginal\: number=10y+x}

\tt{\implies The\: reversed\: number=10x+y}

\sf\large\underline\purple{To\: Find:-}

\tt{\implies The\: orginal\: number=?}

\sf\large\underline\purple{Solution:-}

  • To calculate the ORIGINAL number at FIRST we have to set up equation with the HELP of given clue in the QUESTION. Then calculate the value of x and y after that find out the original number:-]

\sf\small\underline\red{Given\:in\:case\:(i):-}

\tt{\implies sum\:of\:2\: digits=9}

\tt{\implies x+y=9----(i)}

\sf\small\underline\red{Given\:in\:case\:(i):-}

\tt{\implies orginal\: number+45=reversed\: number}

\tt{\implies 10y+x+45=10x+y}

\tt{\implies 10x-x+y-10y=45}

\tt{\implies 9x-9y=45}

  • Here dividing by 9 on both sides:-]

\tt{\implies x-y=5----(ii)}

  • In eq (i) and (ii) solving by adding:-}

\tt{\implies x+y=9}

\tt{\implies x-y=5}

  • By solving we get here:-]

\tt{\implies 2x=14}

\tt{\implies x=7}

  • In eq (i) putting the value of x=7:-]

\tt{\implies x+y=9}

\tt{\implies x+7=9}

\tt{\implies x=9-7}

\tt{\implies x=2}

\sf\large{Hence,}

\tt{\implies Orginal\: number=10y+x}

\tt{\implies Orginal\: number=10*7+2}

\tt{\implies Orginal\: number=70+2}

\tt{\implies Orginal\: number=72}



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