math help

What is 4/12 - 4/9?

What is 4/12 - 4/9?

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

4
12
4
9

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 4 by 9, and get 36.

Then we multiply 4 by 12, and get 48.

Next we give both terms new denominators -- 12 × 9 = 108.

So now our fractions look like this:

36
108
48
108

Step 2

Since our denominators match, we can subtract the numerators.

36 − 48 = -12

So the answer is:

-12
108

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
108
÷ 2 =
-6
54

Let's try dividing by 2 again...

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

-6
54
÷ 2 =
-3
27

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
27
÷ 3 =
-1
9

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:
4
12
4
9
=
1
9