math help

What is 99/7 + 3/9?

What is 99/7 + 3/9?

This is how to add

99
7
+
3
9

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 9, and get 891, then we multiply 7 by 9 and get 63.

99/7 times 9

Do the same for the second term. We multiply 3 by 7, and get 21, then multiply 7 by 9 and get 63.

3/9 times 7

The problem now has new fractions to add:

891
63
+
21
63

Step 2

Since our denominators match, we can add the numerators.

891 + 21 = 912

The sum we get is

912
63

Step 3

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

To find out, we try dividing 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:

912
63
÷ 3 =
304
21

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...

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

Congratulations! Here's your final answer to 99/7 + 3/9

99
7
+
3
9
=
304
21
© 2014 Randy Tayler