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What is 100/24 - 9/12?

What is 100/24 - 9/12?

Here's how to subtract 9/12 from 100/24:

100
24
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 100 by 12, and get 1200.

Then we multiply 9 by 24, and get 216.

Next we give both terms new denominators -- 24 × 12 = 288.

So now our fractions look like this:

1200
288
216
288

Step 2

Since our denominators match, we can subtract the numerators.

1200 − 216 = 984

So the answer is:

984
288

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:

984
288
÷ 2 =
492
144

Let's try dividing by 2 again...

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

492
144
÷ 2 =
246
72

Let's try dividing by 2 again...

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

246
72
÷ 2 =
123
36

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:

123
36
÷ 3 =
41
12

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 12. So we're done reducing.

There you have it! The final answer is:
100
24
9
12
=
41
12