Here's how to subtract 1/3 from 3/9:


Step 1We can't subtract two fractions with different denominators. So you need to get a common denominator. To do this, you'll multiply the denominators times each other... but the numerators have to change, too. They get multiplied by the other term's denominator. So we multiply 3 by 3, and get 9. Then we multiply 1 by 9, and get 9. Next we give both terms new denominators  9 × 3 = 27. So now our fractions look like this:


Step 2Since our denominators match, we can subtract the numerators. 9 − 9 = 0 So the answer is:


Zero divided by anything is just zero. So that's the final answer: 0 