Here's how to subtract 3/9 from 4/12:


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 4 by 9, and get 36. Then we multiply 3 by 12, and get 36. Next we give both terms new denominators  12 × 9 = 108. So now our fractions look like this:


Step 2Since our denominators match, we can subtract the numerators. 36 − 36 = 0 So the answer is:


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