Question 840901
2-digit number: AB


AB = 24
10A + B + 18 = 10B + A ----> 9A - 9B = -18 ---> A - B = -2


Substitute A = B - 2 into the first equation.


(B-2)(B) = 24
B^2 - 2B - 24 = 0
(B - 6)(B + 4) = 0


The digits have to be positive, so B = 6 and A = 4.


The number is AB = 46.