math help

What is 78/10 + 8/12?

What is 78/10 + 8/12?

This is how we add

78
10
+
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 78 by 12, and get 936, then we multiply 10 by 12 and get 120.

78/10 times 12

Do the same for the second term. We multiply 8 by 10, and get 80, then multiply 10 by 12 and get 120.

8/12 times 10

So now our fractions look like this:

936
120
+
80
120

Step 2

Since our denominators match, we can add the numerators.

936 + 80 = 1016

Now we have an answer.

1016
120

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:

1016
120
÷ 2 =
508
60

Let's try dividing by that again...

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

508
60
÷ 2 =
254
30

Let's try dividing by that again...

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

254
30
÷ 2 =
127
15

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...

No good. 17 is larger than 15. So we're done reducing.

There you have it! Here's the final answer to 78/10 + 8/12

78
10
+
8
12
=
127
15
© 2014 Randy Tayler