math help

What is 31/12 + 5/9?

What is 31/12 + 5/9?

Let's add

31
12
+
5
9

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 31 by 9, and get 279, then we multiply 12 by 9 and get 108.

31/12 times 9

Now for the second term. You multiply 5 by 12, and get 60, then multiply 12 by 9 and get 108.

5/9 times 12

This gives us a new problem that looks like so:

279
108
+
60
108

Step 2

Since our denominators match, we can add the numerators.

279 + 60 = 339

That gives us an answer of

339
108

Step 3

Can this fraction be reduced?

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:

339
108
÷ 3 =
113
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 31/12 + 5/9

31
12
+
5
9
=
113
36
© 2014 Randy Tayler