Question

the sum of the two digit number is 7. if the digit are reversed, the original number formed is 9 less than the original number. find the number

Answer 1

let the number be 10x+y
therefore x+y=7
10x+y-(10y+x)=9
9x-9y=9
x-y=1
on solving we get x=4 and y= 3
therefore the original number =43
check the question u have made a mistake

Answer 2

two digits formula.
(10a+b) where a & b is unknown number!!
so hope so with the help of formula you find your answer because if I solve it then you become dependent. so just try to do it from your own