Question

a number consists of two digits.the digits at the tens place is twice that of the digit at units placeif 18 is subtacted from the number the digits are reversed.find the number

Answer 1

let the unit digit be x

∴ tens digit will be 2x

∴ the nos is { 10×[2x] +x}

∴the nos is { 20x +x}

∴the nos is { 21x}

ATP

⇒21x-18 =10x+2x  

⇒21x-18 =12x

⇒21x-12x =18

⇒9x=18

⇒x=18/9  =2

x=2  [unit digit]

tens digit = 2x =2×2  = 4

∴ the nos is 42 ANS