Here's how to subtract 4/10 from 2/5:
We 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 2 by 10, and get 20.
Then we multiply 4 by 5, and get 20.
Next we give both terms new denominators -- 5 × 10 = 50.
So now our fractions look like this:
Since our denominators match, we can subtract the numerators.
20 − 20 = 0
So the answer is:
|Zero divided by anything is just zero. So that's the final answer:|