math help

What is 7/14 + 9/12?

What is 7/14 + 9/12?

Here's how to add

7
14
+
9
12

Step 1

Of course, you can't add two fractions if the denominators (bottom numbers) don't match. To get a common denominator, multiply the denominators together. Then we fix the numerators by multiplying each one by their other term's denominator.

Now you multiply 7 by 12, and get 84, then we multiply 14 by 12 and get 168.

7/14 times 12

Do the same for the second term. We multiply 9 by 14, and get 126, then multiply 14 by 12 and get 168.

9/12 times 14

The problem now has new fractions to add:

84
168
+
126
168

Step 2

Since our denominators match, we can add the numerators.

84 + 126 = 210

This yields the answer

210
168

Step 3

The last step is to reduce the fraction if we can.

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:

210
168
÷ 2 =
105
84

Let's try dividing by that again...

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

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

105
84
÷ 3 =
35
28

Let's try dividing by that again...

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

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

Are both the numerator and the denominator evenly divisible by 7? Yes! So we reduce it:

35
28
÷ 7 =
5
4

Let's try dividing by that again...

No good. 7 is larger than 5. So we're done reducing.

There you have it! Here's the final answer to 7/14 + 9/12

7
14
+
9
12
=
5
4
© 2014 Randy Tayler