math help

What is 99/7 + 9/12?

What is 99/7 + 9/12?

Let's add

99
7
+
9
12

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 99 by 12, and get 1188, then we multiply 7 by 12 and get 84.

99/7 times 12

Now for the second term. You multiply 9 by 7, and get 63, then multiply 7 by 12 and get 84.

9/12 times 7

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

1188
84
+
63
84

Step 2

Since our denominators match, we can add the numerators.

1188 + 63 = 1251

That gives us the sum, which is

1251
84

Step 3

Now, do we need to simplify this fraction?

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

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

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

1251
84
÷ 3 =
417
28

Now, try the same number again.

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...

No good. 29 is larger than 28. So we're done reducing.

Congratulations! Here's your final answer to 99/7 + 9/12

99
7
+
9
12
=
417
28
© 2014 Randy Tayler