math help

What is 11/12 + 7/9?

What is 11/12 + 7/9?

Here's how we add

11
12
+
7
9

Step 1

Can you add yet? Nope! The denominators don't match. We need a common denominator. So next we take both denominators and multiply them. Next, take each numerator and multiply it by the denominator of the other term.

So, we multiply 11 by 9, and get 99, then we multiply 12 by 9 and get 108.

11/12 times 9

Now for the second term. You multiply 7 by 12, and get 84, then multiply 12 by 9 and get 108.

7/9 times 12

We now have a new problem, that looks like this:

99
108
+
84
108

Step 2

Since our denominators match, we can add the numerators.

99 + 84 = 183

That gives us the sum, which is

183
108

Step 3

Now, do we need to simplify this fraction?

First, we attempt to divide it by 2...

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

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

183
108
÷ 3 =
61
36

Let's try dividing by that again...

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

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 36. So we're done reducing.

There you have it! Here's the final answer to 11/12 + 7/9

11
12
+
7
9
=
61
36
© 2014 Randy Tayler