The satisfied numbers are :

10 ; 20 ; 30 ; ... ; 90

11 ; 22 ; 33 ; ... ; 99

12 ; 13 ; 14 ; ... ; 19

24 ; 26 ; 28

36 ; 39

48

There are : 9 + 9 + 8 + 3 + 2 + 1 = 32 (satisfied numbers)

The answer is : \(\dfrac{32}{99-10+1}=\dfrac{32}{90}=\dfrac{16}{45}\)

The answer is \(\dfrac{9}{90-1}=\dfrac{9}{89}\) because eliminate number 10 because the units digit is 0, but the tens digit not is 0