math help

What is 4/10 - 2/8?

What is 4/10 - 2/8?

Here's how to subtract 2/8 from 4/10:

4
10
2
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 4 by 8, and get 32.

Then we multiply 2 by 10, and get 20.

Next we give both terms new denominators -- 10 × 8 = 80.

So now our fractions look like this:

32
80
20
80

Step 2

Since our denominators match, we can subtract the numerators.

32 − 20 = 12

So the answer is:

12
80

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
80
÷ 2 =
6
40

Let's try dividing by 2 again...

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

6
40
÷ 2 =
3
20

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:
4
10
2
8
=
3
20