math help

What is 49/10 - 45/4?

What is 49/10 - 45/4?

Here's how to subtract 45/4 from 49/10:

49
10
45
4

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 49 by 4, and get 196.

Then we multiply 45 by 10, and get 450.

Next we give both terms new denominators -- 10 × 4 = 40.

So now our fractions look like this:

196
40
450
40

Step 2

Since our denominators match, we can subtract the numerators.

196 − 450 = -254

So the answer is:

-254
40

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:

-254
40
÷ 2 =
-127
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...

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...

Nope! So now we try the next greatest prime number, 17...

Nope! So now we try the next greatest prime number, 19...

Nope! So now we try the next greatest prime number, 23...

No good. 23 is larger than 20. So we're done reducing.

There you have it! The final answer is:
49
10
45
4
=
127
20