 # What is 3/12 - 1/8? Here's how to subtract 1/8 from 3/12:

 3 12
 1 8

## Step 1

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 3 by 8, and get 24.

Then we multiply 1 by 12, and get 12.

Next we give both terms new denominators -- 12 × 8 = 96.

So now our fractions look like this:

 24 96
 12 96

## Step 2

Since our denominators match, we can subtract the numerators.

24 − 12 = 12

So the answer is:

 12 96

## Step 3

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:

 12 96
÷ 2 =
 6 48

Let's try dividing by 2 again...

Are both the numerator and the denominator evenly divisible by 2? Yes! So we reduce it:

 6 48
÷ 2 =
 3 24

Let's try dividing by 2 again...

Nope! So now we try the next greatest prime number, 3...

Are both the numerator and the denominator evenly divisible by 3? Yes! So we reduce it:

 3 24
÷ 3 =
 1 8

Let's try dividing by 3 again...

No good. 3 is larger than 1. So we're done reducing.

There you have it! The final answer is:
 3 12
 1 8
=
 1 8