math help

What is 5/100 - 9/12?

What is 5/100 - 9/12?

Here's how to subtract 9/12 from 5/100:

5
100
9
12

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 5 by 12, and get 60.

Then we multiply 9 by 100, and get 900.

Next we give both terms new denominators -- 100 × 12 = 1200.

So now our fractions look like this:

60
1200
900
1200

Step 2

Since our denominators match, we can subtract the numerators.

60 − 900 = -840

So the answer is:

-840
1200

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:

-840
1200
÷ 2 =
-420
600

Let's try dividing by 2 again...

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

-420
600
÷ 2 =
-210
300

Let's try dividing by 2 again...

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

-210
300
÷ 2 =
-105
150

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:

-105
150
÷ 3 =
-35
50

Let's try dividing by 3 again...

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

Are both the numerator and the denominator evenly divisible by 5? Yes! So we reduce it:

-35
50
÷ 5 =
-7
10

Let's try dividing by 5 again...

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

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

No good. 11 is larger than -7. So we're done reducing.

There you have it! The final answer is:
5
100
9
12
=
7
10