math help

What is 15/60 + 5/9?

What is 15/60 + 5/9?

Here's how you add

15
60
+
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 15 by 9, and get 135, then we multiply 60 by 9 and get 540.

15/60 times 9

Now for the second term. You multiply 5 by 60, and get 300, then multiply 60 by 9 and get 540.

5/9 times 60

This gives us a new problem that looks like so:

135
540
+
300
540

Step 2

Since our denominators match, we can add the numerators.

135 + 300 = 435

That gives us an answer of

435
540

Step 3

Can this fraction be reduced?

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

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

Are both the numerator and the denominator evenly divisible by 3? Yes! So we reduce it:

435
540
÷ 3 =
145
180

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 5...

Are both the numerator and the denominator evenly divisible by 5? Yes! So we reduce it:

145
180
÷ 5 =
29
36

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 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. 31 is larger than 29. So we're done reducing.

And we're done! Here's the final answer to 15/60 + 5/9

15
60
+
5
9
=
29
36
© 2014 Randy Tayler