math help

What is 57/7 + 9/12?

What is 57/7 + 9/12?

Let's add

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

57/7 times 12

Now for the second term. You multiply 9 by 7, and get 63, then multiply 7 by 12 and get 84.

9/12 times 7

This gives us a new problem that looks like so:

684
84
+
63
84

Step 2

Since our denominators match, we can add the numerators.

684 + 63 = 747

So what's the answer so far?

747
84

Step 3

Can this fraction be reduced?

First, we attempt to divide 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:

747
84
÷ 3 =
249
28

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...

No good. 29 is larger than 28. So we're done reducing.

Congratulations! Here's your final answer to 57/7 + 9/12

57
7
+
9
12
=
249
28
© 2014 Randy Tayler