Question

THE SUM OF TWO DIGIT NUMBER IS 9 ALSO THE 9 TI THIS NUMBER IS TWICE THE NUMBER OBTAINED THE REVERSED NUMBER FIND THE TWO DIGIT NUMBER

Answer 1

Let once digit number =x
let tenth digit number =y
number = y into 10 +x into 1
10y +x
after interchanging the digits
number = 10 into x+ 1 into y
= 10x+ y
now,
according to question,
x+y =9 -(1) equation
9(10y+x)= 2(10x+y)
90y+9x=20x +2y
90y-2y= 20x- 9x
88y= 11x
11x - 88y =0
x - 8y =0. -(2) equation)
* (taking 11 as common)
by elimination method subtract
x + y =9
x - 8y = 0
(-) (+)= (-)
__________
9y = 9
y = 9/9
y= 1
put the value of 'y'in equation -(1)
x +1= 9
x= 9-1
x= 8
hence, number = 10y + x
= 10 into 1+ 1 into 8
= 10+ 8
= 18