math help

What is 78/10 + 5/7?

What is 78/10 + 5/7?

This is how you add

78
10
+
5
7

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 7, and get 546, then we multiply 10 by 7 and get 70.

78/10 times 7

Do the same for the second term. We multiply 5 by 10, and get 50, then multiply 10 by 7 and get 70.

5/7 times 10

So now our fractions look like this:

546
70
+
50
70

Step 2

Since our denominators match, we can add the numerators.

546 + 50 = 596

Now we have an answer.

596
70

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:

596
70
÷ 2 =
298
35

Now, try the same number again.

Nope. Try the next prime number, 3...

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...

Nope. Try the next prime number, 31...

Nope. Try the next prime number, 37...

No good. 37 is larger than 35. So we're done reducing.

Congratulations! Here's your final answer to 78/10 + 5/7

78
10
+
5
7
=
298
35
© 2014 Randy Tayler