math help

What is 15/11 + 3/9?

What is 15/11 + 3/9?

This is how we add

15
11
+
3
9

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 9, and get 135, then we multiply 11 by 9 and get 99.

15/11 times 9

Do the same for the second term. We multiply 3 by 11, and get 33, then multiply 11 by 9 and get 99.

3/9 times 11

The problem now has new fractions to add:

135
99
+
33
99

Step 2

Since our denominators match, we can add the numerators.

135 + 33 = 168

The sum we get is

168
99

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:

168
99
÷ 3 =
56
33

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. So next you try the next prime number, which is 29...

No good. So next you try the next prime number, which is 31...

No good. So next you try the next prime number, which is 37...

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

And we're done! Here's the final answer to 15/11 + 3/9

15
11
+
3
9
=
56
33
© 2014 Randy Tayler