Here's how to subtract 6/7 from 6/8:
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 6 by 7, and get 42.
Then we multiply 6 by 8, and get 48.
Next we give both terms new denominators -- 8 × 7 = 56.
So now our fractions look like this:
Since our denominators match, we can subtract the numerators.
42 − 48 = -6
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...
Are both the numerator and the denominator evenly divisible by 2? Yes! So we reduce it:
Let's try dividing by 2 again...
Nope! So now we try the next greatest prime number, 3...
Nope! So now we try the next greatest prime number, 5...
No good. 5 is larger than -3. So we're done reducing.There you have it! The final answer is: