This question is taken from linear equations in two variables in which we have to find the number a two digit number is such that the product of its digits is 18. When 63 is subtracted from the number. the digits interchange their places.
Kindly give me a detailed solution of this question
Book – RS Aggarwal, Class 10, chapter 3E, question no 17
Let the tenth digit be x. Then, the units digits=18/x
Number =10x+18/x
and Number obtained by interchanging the digits=10x×18/x+x
∴(10x+18/x)−(10×18/x+x)=63
⇒10x+18/x−180/x−x=63
⇒9x−162/x−63=0
⇒9x²−63x−162=0
⇒x²−7x−18=0
⇒x=9
or x=−2
But, a digit can never be negative, So, x=9
hene, the required number =(10×9)+18/9=92