Answer: 4/9
Step-by-step explanation: Since our denominators in this problem are 9 and 3, and 9 factors as 3 x 3, they have a common factor of 3 so we find their least common denominator by multiplying the 3 that comes from the 3's that match up times the 3 that doesn't match up so we have 3 x 3 or 9.
In order to get a common denominator of 9 for both our fractions, we multiply top and bottom of the the second fraction by 3 and we have 7/9 - 3/9 which simplifies to 4/9. So 7/9 - 1/3 is 4/9.
I have also attached my work in the image provided.
