math help

What is 20/17 + 3/12?

What is 20/17 + 3/12?

This is how we add

20
17
+
3
12

Step 1

We can't add two fractions with different denominators (the bottom number). So you need to get a common denominator - both bottom numbers need to match. To do this, you'll multiply the denominators times each other... but the numerators have to change, too. They get multiplied by the other term's denominator.

So we multiply 20 by 12, and get 240, then we multiply 17 by 12 and get 204.

20/17 times 12

Do the same for the second term. We multiply 3 by 17, and get 51, then multiply 17 by 12 and get 204.

3/12 times 17

So now our fractions look like this:

240
204
+
51
204

Step 2

Since our denominators match, we can add the numerators.

240 + 51 = 291

Now we have an answer.

291
204

Step 3

Last of all, we need to simplify the fraction, if possible. Can it be reduced to a simpler fraction?

To find out, we try dividing it by 2...

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

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

291
204
÷ 3 =
97
68

Now, try the same number again.

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...

Nope. Try the next prime number, 29...

Nope. Try the next prime number, 31...

Nope. Try the next prime number, 37...

Nope. Try the next prime number, 41...

Nope. Try the next prime number, 43...

Nope. Try the next prime number, 47...

Nope. Try the next prime number, 53...

Nope. Try the next prime number, 59...

Nope. Try the next prime number, 61...

Nope. Try the next prime number, 67...

Nope. Try the next prime number, 71...

No good. 71 is larger than 68. So we're done reducing.

Congratulations! Here's your final answer to 20/17 + 3/12

20
17
+
3
12
=
97
68
© 2014 Randy Tayler