math help

What is 24/5 + 9/12?

What is 24/5 + 9/12?

Let's add

24
5
+
9
12

Step 1

Of course, you can't add two fractions if the denominators (bottom numbers) don't match. To get a common denominator, multiply the denominators together. Then we fix the numerators by multiplying each one by their other term's denominator.

Now you multiply 24 by 12, and get 288, then we multiply 5 by 12 and get 60.

24/5 times 12

Do the same for the second term. We multiply 9 by 5, and get 45, then multiply 5 by 12 and get 60.

9/12 times 5

The problem now has new fractions to add:

288
60
+
45
60

Step 2

Since our denominators match, we can add the numerators.

288 + 45 = 333

This yields the answer

333
60

Step 3

The last step is to reduce the fraction if we can.

To find out, we try dividing it by 2...

No good. So next you try the next prime number, which is 3...

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

333
60
÷ 3 =
111
20

So far so good... let's try to divide by that number again.

No good. So next you try the next prime number, which is 5...

No good. So next you try the next prime number, which is 7...

No good. So next you try the next prime number, which is 11...

No good. So next you try the next prime number, which is 13...

No good. So next you try the next prime number, which is 17...

No good. So next you try the next prime number, which is 19...

No good. So next you try the next prime number, which is 23...

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

And we're done! Here's the final answer to 24/5 + 9/12

24
5
+
9
12
=
111
20
© 2014 Randy Tayler