math help

What is 25/15 + 5/11?

What is 25/15 + 5/11?

Here's how to add

25
15
+
5
11

Step 1

We can't add two fractions with different denominators (the bottom number). So you need to get a common denominator - both bottom numbers need to match. 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 25 by 11, and get 275, then we multiply 15 by 11 and get 165.

25/15 times 11

Do the same for the second term. We multiply 5 by 15, and get 75, then multiply 15 by 11 and get 165.

5/11 times 15

So now our fractions look like this:

275
165
+
75
165

Step 2

Since our denominators match, we can add the numerators.

275 + 75 = 350

So the answer is:

350
165

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...

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

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

Are both the numerator and the denominator evenly divisible by 5? Yes! So we reduce it:

350
165
÷ 5 =
70
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 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 25/15 + 5/11

25
15
+
5
11
=
70
33
© 2014 Randy Tayler