math help

What is 64/4 + 4/5?

What is 64/4 + 4/5?

Here's how to add

64
4
+
4
5

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 64 by 5, and get 320, then we multiply 4 by 5 and get 20.

64/4 times 5

Now for the second term. You multiply 4 by 4, and get 16, then multiply 4 by 5 and get 20.

4/5 times 4

This gives us a new problem that looks like so:

320
20
+
16
20

Step 2

Since our denominators match, we can add the numerators.

320 + 16 = 336

So what's the answer so far?

336
20

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:

336
20
÷ 2 =
168
10

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:

168
10
÷ 2 =
84
5

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. 7 is larger than 5. So we're done reducing.

And we're done! Here's the final answer to 64/4 + 4/5

64
4
+
4
5
=
84
5
© 2014 Randy Tayler