math help

What is 30/50 + 9/12?

What is 30/50 + 9/12?

This is how we add

30
50
+
9
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 30 by 12, and get 360, then we multiply 50 by 12 and get 600.

30/50 times 12

Now for the second term. You multiply 9 by 50, and get 450, then multiply 50 by 12 and get 600.

9/12 times 50

This gives us a new problem that looks like so:

360
600
+
450
600

Step 2

Since our denominators match, we can add the numerators.

360 + 450 = 810

So what's the answer so far?

810
600

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:

810
600
÷ 2 =
405
300

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...

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

405
300
÷ 3 =
135
100

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:

135
100
÷ 5 =
27
20

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. 23 is larger than 20. So we're done reducing.

And we're done! Here's the final answer to 30/50 + 9/12

30
50
+
9
12
=
27
20
© 2014 Randy Tayler