First of all, you will want to change the fraction to have the same denominator.
The common factor for 9 and 6 is 18. (9x2=18 and 6x3=18) Then, you multiply the numerator by the factor you got in the first step, which is 2 and 3, respectively. So the new fractions areand 7
The next step is to simply subtract the mixed numbers! - = 1 1/18