Question

the sum of digits of a two digit number is 15. the number obtained by interchanging the digit exceeds the given number by 9. find the number


or
solve x and y

$\frac{x}{a} + \frac{y}{b} = 2 \\ ax - by = { a}^{2} - { b}^{2}$

Answer 1

X+y=15 -eq 1


10y+x=10x+y+9


9y-9x=9


y-x=1 -eq 2


x + y = 15


-x + y = 1


2y = 16


y=8


put value of y in eq 1


x+8=15


x=15-8


x=7


GN = 87

Answer 2

15*15-9*9
225-81
= 144