math help

What is 15/11 + 8/12?

What is 15/11 + 8/12?

Here's how we add

15
11
+
8
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 15 by 12, and get 180, then we multiply 11 by 12 and get 132.

15/11 times 12

Do the same for the second term. We multiply 8 by 11, and get 88, then multiply 11 by 12 and get 132.

8/12 times 11

The problem now has new fractions to add:

180
132
+
88
132

Step 2

Since our denominators match, we can add the numerators.

180 + 88 = 268

The sum we get is

268
132

Step 3

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

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:

268
132
÷ 2 =
134
66

Now, try the same number again.

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

134
66
÷ 2 =
67
33

Now, try the same number again.

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

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...

Nope. Try the next prime number, 19...

Nope. Try the next prime number, 23...

Nope. Try the next prime number, 29...

Nope. Try the next prime number, 31...

Nope. Try the next prime number, 37...

No good. 37 is larger than 33. So we're done reducing.

Congratulations! Here's your final answer to 15/11 + 8/12

15
11
+
8
12
=
67
33
© 2014 Randy Tayler