math help

What is 4/10 - 3/9?

What is 4/10 - 3/9?

Here's how to subtract 3/9 from 4/10:

4
10
3
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 3 by 10, and get 30.

Next we give both terms new denominators -- 10 × 9 = 90.

So now our fractions look like this:

36
90
30
90

Step 2

Since our denominators match, we can subtract the numerators.

36 − 30 = 6

So the answer is:

6
90

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:

6
90
÷ 2 =
3
45

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
45
÷ 3 =
1
15

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
10
3
9
=
1
15