math help

What is 9/12 - 4/8?

What is 9/12 - 4/8?

Here's how to subtract 4/8 from 9/12:

9
12
4
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 9 by 8, and get 72.

Then we multiply 4 by 12, and get 48.

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

So now our fractions look like this:

72
96
48
96

Step 2

Since our denominators match, we can subtract the numerators.

72 − 48 = 24

So the answer is:

24
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:

24
96
÷ 2 =
12
48

Let's try dividing by 2 again...

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

12
48
÷ 2 =
6
24

Let's try dividing by 2 again...

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

6
24
÷ 2 =
3
12

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
12
÷ 3 =
1
4

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:
9
12
4
8
=
1
4