math help

What is 78/10 + 6/8?

What is 78/10 + 6/8?

Here's how we add

78
10
+
6
8

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 78 by 8, and get 624, then we multiply 10 by 8 and get 80.

78/10 times 8

Do the same for the second term. We multiply 6 by 10, and get 60, then multiply 10 by 8 and get 80.

6/8 times 10

The problem now has new fractions to add:

624
80
+
60
80

Step 2

Since our denominators match, we can add the numerators.

624 + 60 = 684

The sum we get is

684
80

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:

684
80
÷ 2 =
342
40

Let's try dividing by that again...

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

342
40
÷ 2 =
171
20

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 20. So we're done reducing.

There you have it! Here's the final answer to 78/10 + 6/8

78
10
+
6
8
=
171
20
© 2014 Randy Tayler