math help

What is 25/15 + 9/11?

What is 25/15 + 9/11?

Here's how we add

25
15
+
9
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 9 by 15, and get 135, then multiply 15 by 11 and get 165.

9/11 times 15

So now our fractions look like this:

275
165
+
135
165

Step 2

Since our denominators match, we can add the numerators.

275 + 135 = 410

Now we have an answer.

410
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...

Nope! So now we try the next greatest prime number, 3...

Nope! So now we try the next greatest prime number, 5...

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

410
165
÷ 5 =
82
33

Let's try dividing by that again...

Nope! So now we try the next greatest prime number, 7...

Nope! So now we try the next greatest prime number, 11...

Nope! So now we try the next greatest prime number, 13...

Nope! So now we try the next greatest prime number, 17...

Nope! So now we try the next greatest prime number, 19...

Nope! So now we try the next greatest prime number, 23...

Nope! So now we try the next greatest prime number, 29...

Nope! So now we try the next greatest prime number, 31...

Nope! So now we try the next greatest prime number, 37...

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

There you have it! Here's the final answer to 25/15 + 9/11

25
15
+
9
11
=
82
33
© 2014 Randy Tayler