Question 630266
digits: xy

x is the tens digit

number represented : 10x + y 

y = 2 + x

the tens digit must be smaller than the ones digit to give a positive difference: 

yx - xy 

10y + x - (10x + y) = 18

10(2 + x) + x - 10x - 2 - x = 18

20 + 10x + x - 10x -2 -x = 18

18=18, cannot be solved explicitly algebraically; must use iteration

13

31 - 13 = 18

24

42 - 24 = 18

35

53 - 35 = 18

46

64 - 46 = 18

Works for ANY 2 digit number such that XY, Y = X+2