math help

What is 7/20 + 2/12?

What is 7/20 + 2/12?

This is how to add

7
20
+
2
12

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 7 by 12, and get 84, then we multiply 20 by 12 and get 240.

7/20 times 12

Now for the second term. You multiply 2 by 20, and get 40, then multiply 20 by 12 and get 240.

2/12 times 20

This gives us a new problem that looks like so:

84
240
+
40
240

Step 2

Since our denominators match, we can add the numerators.

84 + 40 = 124

That gives us an answer of

124
240

Step 3

Can this fraction be reduced?

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

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

124
240
÷ 2 =
62
120

So far so good... let's try to divide by that number again.

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

62
120
÷ 2 =
31
60

So far so good... let's try to divide by that number again.

No good. So next you try the next prime number, which is 3...

No good. So next you try the next prime number, which is 5...

No good. So next you try the next prime number, which is 7...

No good. So next you try the next prime number, which is 11...

No good. So next you try the next prime number, which is 13...

No good. So next you try the next prime number, which is 17...

No good. So next you try the next prime number, which is 19...

No good. So next you try the next prime number, which is 23...

No good. So next you try the next prime number, which is 29...

No good. So next you try the next prime number, which is 31...

No good. So next you try the next prime number, which is 37...

No good. 37 is larger than 31. So we're done reducing.

And we're done! Here's the final answer to 7/20 + 2/12

7
20
+
2
12
=
31
60
© 2014 Randy Tayler