What is 3/12 + 2/5?

Let's add

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 3 by 5, and get 15, then we multiply 12 by 5 and get 60.

Do the same for the second term. We multiply 2 by 12, and get 24, then multiply 12 by 5 and get 60.

The problem now has new fractions to add:

Step 2

Since our denominators match, we can add the numerators.

15 + 24 = 39

The sum we get is

Step 3

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

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

Nope. Try the next prime number, 3...

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

Now, try the same number again.

Nope. Try the next prime number, 5...

Nope. Try the next prime number, 7...

Nope. Try the next prime number, 11...

Nope. Try the next prime number, 13...

Nope. Try the next prime number, 17...

No good. 17 is larger than 13. So we're done reducing.

Congratulations! Here's your final answer to 3/12 + 2/5