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What is 2/12 - 3/10?

What is 2/12 - 3/10?

Here's how to subtract 3/10 from 2/12:

2
12
3
10

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 2 by 10, and get 20.

Then we multiply 3 by 12, and get 36.

Next we give both terms new denominators -- 12 × 10 = 120.

So now our fractions look like this:

20
120
36
120

Step 2

Since our denominators match, we can subtract the numerators.

20 − 36 = -16

So the answer is:

-16
120

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:

-16
120
÷ 2 =
-8
60

Let's try dividing by 2 again...

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

-8
60
÷ 2 =
-4
30

Let's try dividing by 2 again...

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

-4
30
÷ 2 =
-2
15

Let's try dividing by 2 again...

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:
2
12
3
10
=
2
15