math help

What is 7/20 + 6/8?

What is 7/20 + 6/8?

This is how to add

7
20
+
6
8

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 8, and get 56, then we multiply 20 by 8 and get 160.

7/20 times 8

Now for the second term. You multiply 6 by 20, and get 120, then multiply 20 by 8 and get 160.

6/8 times 20

This gives us a new problem that looks like so:

56
160
+
120
160

Step 2

Since our denominators match, we can add the numerators.

56 + 120 = 176

That gives us an answer of

176
160

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:

176
160
÷ 2 =
88
80

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:

88
80
÷ 2 =
44
40

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:

44
40
÷ 2 =
22
20

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:

22
20
÷ 2 =
11
10

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. 11 is larger than 10. So we're done reducing.

And we're done! Here's the final answer to 7/20 + 6/8

7
20
+
6
8
=
11
10
© 2014 Randy Tayler