math help

What is 3/20 + 2/12?

What is 3/20 + 2/12?

This is how you add

3
20
+
2
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 3 by 12, and get 36, then we multiply 20 by 12 and get 240.

3/20 times 12

Now for the second term. You multiply 2 by 20, and get 40, then multiply 20 by 12 and get 240.

2/12 times 20

This gives us a new problem that looks like so:

36
240
+
40
240

Step 2

Since our denominators match, we can add the numerators.

36 + 40 = 76

So what's the answer so far?

76
240

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:

76
240
÷ 2 =
38
120

Now, try the same number again.

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

38
120
÷ 2 =
19
60

Now, try the same number again.

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

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

Nope. Try the next prime number, 7...

Nope. Try the next prime number, 11...

Nope. Try the next prime number, 13...

Nope. Try the next prime number, 17...

Nope. Try the next prime number, 19...

Nope. Try the next prime number, 23...

No good. 23 is larger than 19. So we're done reducing.

Congratulations! Here's your final answer to 3/20 + 2/12

3
20
+
2
12
=
19
60
© 2014 Randy Tayler