math help

What is 72/63 - 6/8?

What is 72/63 - 6/8?

Here's how to subtract 6/8 from 72/63:

72
63
6
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 72 by 8, and get 576.

Then we multiply 6 by 63, and get 378.

Next we give both terms new denominators -- 63 × 8 = 504.

So now our fractions look like this:

576
504
378
504

Step 2

Since our denominators match, we can subtract the numerators.

576 − 378 = 198

So the answer is:

198
504

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:

198
504
÷ 2 =
99
252

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:

99
252
÷ 3 =
33
84

Let's try dividing by 3 again...

Are both the numerator and the denominator evenly divisible by 3? Yes! So we reduce it:

33
84
÷ 3 =
11
28

Let's try dividing by 3 again...

Nope! So now we try the next greatest prime number, 5...

Nope! So now we try the next greatest prime number, 7...

Nope! So now we try the next greatest prime number, 11...

Nope! So now we try the next greatest prime number, 13...

No good. 13 is larger than 11. So we're done reducing.

There you have it! The final answer is:
72
63
6
8
=
11
28