math help

What is 12/13 + 5/7?

What is 12/13 + 5/7?

This is how you add

12
13
+
5
7

Step 1

We still have different denominators (bottom numbers), though, so we need to get a common denominator. This will make the bottom numbers match. Multiply the denominators together first. Now, multiply each numerator by the other term's denominator.

Now we multiply 12 by 7, and get 84, then we multiply 13 by 7 and get 91.

12/13 times 7

Now for the second term. You multiply 5 by 13, and get 65, then multiply 13 by 7 and get 91.

5/7 times 13

This gives us a new problem that looks like so:

84
91
+
65
91

Step 2

Since our denominators match, we can add the numerators.

84 + 65 = 149

So what's the answer so far?

149
91

Step 3

Can this fraction be reduced?

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

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

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...

Nope. Try the next prime number, 31...

Nope. Try the next prime number, 37...

Nope. Try the next prime number, 41...

Nope. Try the next prime number, 43...

Nope. Try the next prime number, 47...

Nope. Try the next prime number, 53...

Nope. Try the next prime number, 59...

Nope. Try the next prime number, 61...

Nope. Try the next prime number, 67...

Nope. Try the next prime number, 71...

Nope. Try the next prime number, 73...

Nope. Try the next prime number, 79...

Nope. Try the next prime number, 83...

Nope. Try the next prime number, 89...

Nope. Try the next prime number, 97...

No good. 97 is larger than 91. So we're done reducing.

Congratulations! Here's your final answer to 12/13 + 5/7

12
13
+
5
7
=
149
91
© 2014 Randy Tayler