math help

What is 57/7 + 8/12?

What is 57/7 + 8/12?

Here's how to add

57
7
+
8
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 57 by 12, and get 684, then we multiply 7 by 12 and get 84.

57/7 times 12

Do the same for the second term. We multiply 8 by 7, and get 56, then multiply 7 by 12 and get 84.

8/12 times 7

So now our fractions look like this:

684
84
+
56
84

Step 2

Since our denominators match, we can add the numerators.

684 + 56 = 740

Now we have an answer.

740
84

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...

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

740
84
÷ 2 =
370
42

Let's try dividing by that again...

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

370
42
÷ 2 =
185
21

Let's try dividing by that again...

Nope! So now we try the next greatest prime number, 3...

Nope! So now we try the next greatest prime number, 5...

Nope! So now we try the next greatest prime number, 7...

Nope! So now we try the next greatest prime number, 11...

Nope! So now we try the next greatest prime number, 13...

Nope! So now we try the next greatest prime number, 17...

Nope! So now we try the next greatest prime number, 19...

Nope! So now we try the next greatest prime number, 23...

No good. 23 is larger than 21. So we're done reducing.

There you have it! Here's the final answer to 57/7 + 8/12

57
7
+
8
12
=
185
21
© 2014 Randy Tayler