math help

What is 99/7 + 8/12?

What is 99/7 + 8/12?

Here's how to add

99
7
+
8
12

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

99/7 times 12

Do the same for the second term. We multiply 8 by 7, and get 56, then multiply 7 by 12 and get 84.

8/12 times 7

The problem now has new fractions to add:

1188
84
+
56
84

Step 2

Since our denominators match, we can add the numerators.

1188 + 56 = 1244

The sum we get is

1244
84

Step 3

The last step is to reduce the fraction if we can.

To find out, we try dividing it by 2...

Are both the numerator and the denominator evenly divisible by 2? Yes! So we reduce it:

1244
84
÷ 2 =
622
42

Let's try dividing by that again...

Are both the numerator and the denominator evenly divisible by 2? Yes! So we reduce it:

622
42
÷ 2 =
311
21

Let's try dividing by that again...

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

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...

No good. 23 is larger than 21. So we're done reducing.

There you have it! Here's the final answer to 99/7 + 8/12

99
7
+
8
12
=
311
21
© 2014 Randy Tayler