math help

What is 7/20 + 2/8?

What is 7/20 + 2/8?

This is how you add

7
20
+
2
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 2 by 20, and get 40, then multiply 20 by 8 and get 160.

2/8 times 20

This gives us a new problem that looks like so:

56
160
+
40
160

Step 2

Since our denominators match, we can add the numerators.

56 + 40 = 96

So what's the answer so far?

96
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:

96
160
÷ 2 =
48
80

Now, try the same number again.

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

48
80
÷ 2 =
24
40

Now, try the same number again.

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

24
40
÷ 2 =
12
20

Now, try the same number again.

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

12
20
÷ 2 =
6
10

Now, try the same number again.

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

6
10
÷ 2 =
3
5

Now, try the same number again.

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

Nope. Try the next prime number, 5...

No good. 5 is larger than 3. So we're done reducing.

Congratulations! Here's your final answer to 7/20 + 2/8

7
20
+
2
8
=
3
5
© 2014 Randy Tayler