1/8 is greater than 1/9 , because 1 is being divided by a smaller number and hence the result would be bigger than when that same 1 is divided by a bigger number as 9.
OR
1/9 1/8 Cross Multiply
8*1 9*1
8 9
8 < 9
Implies that 1/9 is less than 1/8 and hence 1/8 is greater than 1/9.
OR
Use your calculator and convert both to decimal
1/9 1/8
0.111.. 0.125
You can see that 1/8 is greater than 1/9.