Here's how to subtract 1/7 from 1/9:
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 1 by 7, and get 7.
Then we multiply 1 by 9, and get 9.
Next we give both terms new denominators -- 9 × 7 = 63.
So now our fractions look like this:
Since our denominators match, we can subtract the numerators.
7 − 9 = -2
So the answer is:
Last of all, we need to simplify the fraction, if possible. Can it be reduced to a simpler fraction?
To find out, we try dividing it by 2...
Nope! So now we try the next greatest prime number, 3...
No good. 3 is larger than -2. So we're done reducing.There you have it! The final answer is: