Question

from chapter linear equation in one variable the sum of the digits of two digit number is 7 when the digits are reversed the number is decreased by 9 find the number

Answer 1

as according to Question x+y = 7---- i
Where,
x and y is any two numbers
now,( 10x + y ) -(10y +x) =9
10x +y -10y -x = 9
9x - 9y = 9
9(x-y )= 9
x-y = 1 - ......... ii
now add I and ii
we get, 2x = 8
x= 4
from i
4+y=7
y = 7- 4
y=3
so the digit is 10x +y
10*4+3= 43